N8x0 I can't comment on. It's still on my list to do something about it. I hate having devices without big use in my house. I have a hunch QML apps might work slightly better than MTF.
N900: Only thing expected is the "MeeGo DE" stuff, see the thread for it. That's something at least I would use on day-to-day basis. Even if it has only few, working features at first. And it'd be on a open platform and open applications that anyone can customize. And improve upon too. Perhaps you would be good with this too?
I can't recommend anyone to do a Maemo fork, we all know how that went last time anyone was insane enough to do that