No first hand experience with Kuhl but from looking at cutaways, I see an old fashion window unit paired with an attractive faceplate and updated electronics. There is really nothing innovative with regards to noise control. So they use thin metal instead of styrofoam to isolate the compressor...big deal. It is still going to cycle on with a kick and generate about 50db of noise indoors.

Well they make a LOT of claims about noise isolation. And I know that our 5400btu X-star is far quieter than the 2 ton Maytag, of course that is likely because of the obvious equipment sizing differences...

50dB indoors to me seems awful quiet compared to what I think the Maytag unit makes...

Most manufacturers are in other country's now. Mexico's quality has improved over the last decade in my opinion. China has a long way to go still. Mexican's are hard workers generally. American car company's went to Canada years ago with no complaints so it is all part of the way things are done know.
Take a look at Goodman which is made in Texas and compare that brand with any other that is made in Mexico, they are about the same.

The improved noise isolation they're claiming is a throwback to the way window units were made 25 years ago. Large heavy cabinet, bigger air passage, steel inner wall, thicker rubber grommets. What is needed is a radical redesign of the compressor because the ones now being installed in Friedrich AC's are loud and prone to vibrate

So can we assume that there is noise benefit over a unit from 10 years ago from maytag, especially I'd the rating is slightly lower?

Whether Mexican or Chinese stuff is as good in terms of quality, it's lost American jobs for stuff that we certainly can acquire and build without major issues. My friedrich X-star was US made as we're the models before it.

I'm fairly sure JHZR2 has solved and settled his issues by now and it would be interesting to learn his solution. I live in SW Texas and recently converted from a fairly efficient and quiet Lennox central heat pump system to two Kuhl "through the wall" systems for my downstairs, simply because the cost of replacing the Lennox involved a high installation cost. I no longer use my upstairs and two of the downstairs rooms are seldom used, so the main part of the "in service" area downstairs is a fairly straight shot through a very large bedroom, double door to the kitchen/dining and then double door to the living room. There are peripheral rooms of course, but those three are the main areas affected by the Friedrich Kuhls.

I also considered putting in split mini units in three places downstairs, primarily wanting quiet operation, but my quotes were astronomical... far more than replacing the central system, so the idea was to get two very efficient and powerful units, one at each end of those three areas and then add low priced smaller units in the other areas of dressing/bathroom, office and guest room. I got the Kuhls last September, so I only had a short time of use for cooling mode.

I've had window units before, all fairly small, and back in the 60s had a Chrysler 2-ton in a tiny house I owned that did the entire structure... of about 1100 sqft.

In my memory, not one of those older units EVER made as much noise as the Kuhls. The fans are large and very powerful, but not appreciatively loud, but as soon as the compressors kick in, clunks, buzzes, vibration and the sound of the compressor itself kick in and, especially in the bedroom, are horrible. In addition the temperature control has never been very good. If you have either or both units on automatic, they wait until way past the point that they should turn on and then continue to run way past where they should shut down... resulting in a 4 degree spread on either side of the selected temperature.

I immediately had a warranty issue and Friedrich's nearest contractor was 60 miles from my rural home, and they insisted I bring them the unit because they didn't allow their "boys" to take them out of the wall. I reluctantly did so (I am 76 and my wife is tiny) and all they did was put the unit on a table and pronounce it "no problems".

No I do not recommend you pay nearly $2500 and install these yourself. That's far two much for two small units. Yes they do have remote controls, but those too have issues and I do not use them. You can buy an optional module to get wifi control now too, but I did not explore that. No I am not happy with them, but I'm pretty much stuck with them. I have an LG 8000 BTU unit in the guest room and it is much quieter since it uses a rotary compressor.