The diffs didn't build too well for me...When tightened enough so that they wouldn't slip, they were very stiff.
The drive train is also just as tight as my TC3 was out of the box, although I haven't played with shimming it any other way than the manual says yet. The bearings seem to seat better in the new diff cases, but the diff and pinion gears are too close and cause binding. Unfortunately, if I remember correctly there wasn't much space between the pinion and the diff case, so in order to shim it back enough I think I'm going to have to do some grinding. Exact same thing happened with my TC3.
I love the new steering, very smooth out of the box and it doesn't look like anything will get caught up in there.
Josh