Been using the Cherry profile set on my QFR for a few months now (since the last drop) and it's been great. Took a few days to get used to the Cherry profile, but I use OEM profile at work so it's a change.
YouGotRiotedI too would be dying to get your thoughts as someone who uses both regularly. Does switching back and forth cause issues? Since Cherry is relatively rare as profiles go, I'd hate to throw a kink into the machine for no good reason. Do you find that the contour of Cherry is a bit shallow, especially with the bottom rows? That's one of my worries. I do like the non-beveled edges of the Cherry key caps.
MookNo o-rings, although I haven't tried them with the Cherry profile yet. I've dabbled with them at work on OEM profile but never really found the need since MX browns are relatively quiet even when bottoming out.
FlappyIt's really hard to say since it seems as if most of the thick keysets are all in Cherry profile, e.g. Vortex thick PBT or GMK ABS. I'm really typing on thick keys though.
MookNo issues at all, I think once you get used to both, then there's almost no adjustment time if you're switching between them regularly.
I find Cherry perfectly fine in terms of keycap height and travel, even with the lower rows. DSA on the other hand I just could not get used to, ended up replacing my DSA set with this Vortex PBT set.
FlappyAmazon has great 70A durometer o-rings for $2 shipped (if you have Prime). The high durometer rating means it is less squishy than the overpriced nonsense being sold at certain places. Check out the reviews. http://www.amazon.com/008-Buna-N-O-Ring-Durometer-Black/dp/B000FMWLR8.
These are what I use on my QFR with OEM caps. Awesome feel.
FlappyI've bought 3 sets off this guy and they've been great. He's not far away from me either, so I get them nice and quick. They calmed down my Blackwidow Ultimate nicely.