Stock Experience:

The BSUN Udon utilizes a slightly different pre-lubrication method compared to the rest of BSUN as they wanted to avoid lube pooling issues that appeared in some older releases.

They strictly only applied lubricant on the stem rails (sliders) and slightly over the leaf and spring. The BSUN Udon does perform decently with a minimal amount of lubricant, however I think they probably could have applied some more on the legs or leaf to prevent any ticking noise.

The housing tolerances are quite good and these switch do not require films.

Would I modify them?
Personally no, however I do think that these switches may be able to benefit from a slight addition of lubricant over the leaf just to clean up some of the sound. After having them for quite some time, I just haven't felt affected by the minor ticking compared to some of the older BSUN releases which had noticeable ticking.

Y3X + PA66 Fiberglass bottom:

I think that these materials do play an important part in the relatively bright yet soft sound profile of this switch. (Mostly rounded)

They specifically revealed the bottom housing to be PA66 + 30% fiberglass when the composition for the Usagi and Ragdolls were kept hidden. Though with the difference in sound profile, I can assume that my original guesses for the other two switches to not be far off the mark.

With PA66 being a bit stiffer than the other nylons and containing a fair amount of fiberglass, we can expect the overall pitch and tone to be slightly brighter than the others. This is evident when considering the Ragdolls are slightly quieter, and the Usagi is slightly deeper. It's a marginal difference, but it does make it lean towards the clackier side of switches despite not being particularly sharp.

The Y3X has the largest effect here by being a material comprised of UPE, it will automatically lean a bit towards the muted side, but this helps balance out the fiberglass traits. This leads to a contrasting sound profile where the pitch gets higher and sharper but instead gets compressed or dampened a bit thanks to the Y3X and ends up neither deep nor sharp. 

Overall Design:

These switches have a lot to express despite not being particularly loud, they have a colorful sound profile thanks to the composition and it's a bit refreshing when compared to most of today's releases.

With a PC top housing, the top-out sound is a bit bright thanks to the snappy return of the spring. The bottom-housing combination with stem leads to a poppy and compressed sound, but it isn't much louder than the top-out sound.

As a BSUN switch, it sets itself apart by stepping out from their usual frame of being a "creamy" option with firm and deeper clacks. The BSUN Udon is a livelier version that doesn't have a one-note sound profile and doesn't sound too deep nor too sharp.

It's a good option if you're looking for a switch that's not extremely loud but has some character.

Smoothness and typing experience:

Thanks to the UPE based stem material and fiberglass modification the baseline smoothness of this switch is superb. BSUN's smoothness has proven itself ever since they started releasing their new stuff back in 2023. 

There's not much reason to add more lubricant as you probably won't improve the smoothness much, though perhaps you can deepen the sound profile a bit more.

There is a minor amount of vertical wobble present, but it isn't enough to be a major factor during typing.

It doesn't have BSUN's firm bottom out since it uses a stem material that is slightly softer. With a very balanced spring weight at 55g, you can experience a fairly pleasant typing experience.

Sound Profile:

The BSUN Udon's sound profile is very similar to the Ragdoll and Usagi but with some minor differences. I think that it can still be considered rounded, but just a bit brighter than the other two.

The bottom-out sound profile is glassy but slightly dampened by the Y3X stem, the top-out sound is noticeable but not louder than the bottom-out. The compressed pop noises that you can hear from the switch allow for an overall pleasant experience from a noisier switch than most releases.

Like mentioned earlier, it isn't an especially loud switch, nor is it muted or quiet, it is mostly balanced but leans towards the clackier end of the spectrum.

The BSUN Udon is a slightly unique long-pole release with plenty of character in the sound. With an overall noisy sound profile, crisp and poppy bottom out, and a rounded pitch that doesn't leave you bored, these switches may not be the fullest around, but perhaps this is the one if you're tired of the heavy hitters?

Noisy refers to having multiple facets of sound in the profile, not in a bad way, but the switch can have an audible top-out, scratch, or something else which adds character to the sound.

Crisp refers to having a solid bottom-out that is clear and is easy to hear, doesn't necessarily mean loud and bright.

Rounded refers to having a balanced sound profile that isn't too quiet or loud, nor deep or sharp.

Comparative Notes:

I will break down the comparative strength of this switch when compared to other manufacturers and their average switch releases. Keep in mind that this is not a guaranteed guide, this serves to assist those who don't have a general idea of what to expect from this switch or other manufacturers.

Compared to HMX switches on average:
1. The BSUN Udon is likely to be fuller in sound or similar to a few HMX.
2. The BSUN Udon is likely to be slightly lower pitched than most HMX.
3. The BSUN Udon is likely to be similar volume or slightly quieter than some HMX.
4. The BSUN Udon is likely to be of similar weight or slightly heavier than most HMX.
5. The BSUN Udon is likely to have a slightly worse stock experience than some HMX.
6. The BSUN Udon is likely to have similar smoothness to most HMX.

Compared to Gateron switches on average:
1. The BSUN Udon is likely to be of similar fullness or slightly more full.
2. The BSUN Udon is likely to be higher pitched than most Gateron.
3. The BSUN Udon is likely to be of similar volume or slightly louder than some Gateron.
4. The BSUN Udon is likely to be of similar weight or lighter than some Gateron.
5. The BSUN Udon is likely to be similar stock or slightly worse than some Gateron.
6. The BSUN Udon is similar in smoothness or slightly less smooth than some Gateron.

Compared to BSUN switches on average:
1. The BSUN Udon is likely to be of similar fullness.
2. The BSUN Udon is likely to be slightly higher pitch,
3. The BSUN Udon is likely to be of similar volume or slightly quieter than some BSUN.
4. The BSUN Udon is likely to be of similar weight or heavier than most BSUN.
5. The BSUN Udon is likely to be of similar stock experience.
6. The BSUN Udon is likely to be of similar smoothness or slightly better.

Flaws and things I didn't like:

The only notable flaw would probably be the minor ticking noise. I'm not sure if its from the leaf or something else in particular.

It isn't extremely noticeable during typing because the switch itself can cover up most of the noise. 

There wasn't anything that I didn't like besides the slightly reduced lubricant on the switch, the stem legs don't have much lube on them and neither does the leaf. I would have hoped for slightly more pre-lube but I completely understand BSUN trying to prevent any mishaps from overlube.

PERSONAL BUILD RECOMMENDATIONS: (PREFERENCE/OPINION BASED)

Since these switches are mostly rounded and leaning towards the high pitch, they will fit on almost any plate depending on what you want to achieve. I think that the first time I used them was on a Polycarbonate plate with top mount.

I recently re-tested them on Aluminum and Polypropylene and I think that slightly louder plates will be the way to go since I wanted to boost the volume a bit more.

Mounting style isn't a major concern since they are comfortable to type on and aren't particular firm. I would go for something standard like Aluminum with some form of gasket, whether it's silicone gaskets, tadpole gaskets, or an O-ring gasket.

Foam should be fine to use if that is your preference but just keep aware that it might mute the sound a bit.

Closing Summary:

The BSUN Udon is a bit more unique than the average BSUN release, but still stays true to the overall flavor of BSUN.

I personally find them refreshing as a lot of releases these days are the clean, one-note, and solid sounding bottom-out long poles that fill up the market. I myself am a fan of slightly noisier switches, whether its from scratch or otherwise.

Though BSUN is slightly overshadowed by HMX and Keygeek nowadays, they still produce switches that are different than both of those manufacturers, and there are definitely people out there with different preferences. Not everyone is willing to branch out and try different switches, but I have always been open to variety and I hope that BSUN continues to compete with future releases.

Although the minor ticking is slightly regretful, everything else about this switch is excellent and deserves to be given a shot by newcomers to BSUN. 

If you're in the market for a switch that might not hit as hard as the competition, but is rowdy and has its own personality, the BSUN Udon is my first go-to.

FINAL SCORING: 9.0/10 [Regretful, but still refreshing]