If the difference in feel after replacing the foam were significant or substantial (ie. not negligible), I'd be all for it.
I think that my foam replacements have made a significant improvement in the feel of the keyboard. I did a few XTs and ATs with good-to-acceptable foam mats before I ever touched an F-122. These came apart and went back together by hand without undue heartache, although it was not exactly easy.
Of a dozen of so F-122s I have disassembled, only one had a mat that I would call "good" and perhaps 2-3 were "acceptable" if just barely. I suspect that the small ones had been stored in people's homes in decent conditions and the big boys had been stored in warehouses and other ugly industrial environments.
However, I consider raw Fs in the wild as being "too much" in terms of sound and vibration. A new thick firm mat dampens the vibrations from the center of the internal assembly, where dampening is most effective, and various other mats and padding, moving out from the center, become progressively less effective. I also consider the floss mod essential and have done every one of the Fs in my collection.
None of this is true with Model Ms, of course, because they are generally pretty "dead" to begin with.
As far as cleaning goes, when I take these things apart I use the opportunity to clean every single component as well as possible (I have even occasionally washed spring/hammer/pivot plates in soapy water (dish soap, not the alkaline stuff I use on plastic) although that is seldom necessary). I have never understood all that business about denture tablets when powdered laundry detergent and "oxi" works so well and so quickly. There is also sanding and painting involved as a matter of course.
Like I said before, of the dozen or so F-122s I have re-habbed, there were a couple that were particularly easy, and a couple that were particularly difficult, and one that was a complete nightmare. I do think that the long clamp from Grand Harbor with non-swiveling head will make a tremendous difference.