To save anyone reading the longer blogpost below: current default settings that I've been playing with are fine. Ship it.
The game is undeniably different in a few small ways which is translating to (juggles, at least) being a chunk easier in MM vs TFC, but ultimately, the question the TFC boomers have been discussing the most is simply: is it fun?
That's one thing everyone has agreed on, and feedback is resoundingly positive. Emp played again for a bit yesterday/lastnight and the verdict was basically "I had fun to the point where I want to play again, so I'm happy".
3.8 fuse is fine (and like Zike said above, involves a chunk less work, which is a plus at this point),
mom_conc_use_tfc = 1 is what I've been using since it was implemented. I would say that conc behaviour specifically is in a very good spot, and I think everyone that generally talks about conc stuff would be more than happy with what's currently on the plate.
There's still some rumblings of things like brushing walls killing your speed and being very punishing as a result, but it's not something I've personally looked into yet so if Kanin or Gnu wanted to raise it here or in the channel that'd be good to get more eyes on it.