Not going to lie, i have little-no experience with Reactor. I HAVE however used havok 4, and it is a very simple system, even though i havnt gone deep into that either.
tbh I don't know much about physics engines either. I have used Reactor and Havok as seen in Beth games, and tinkered with HB and physX, but tbh I can't see much wrong with the what havok...6? I think, has in terms of it equivalent in Reactor. It's pretty close.
For those that don't know, reactor is the engine in Max, which is like where most studios author most of their game content with.
I think people are digging at it while not even knowing of a viable alternative or better solution. Let alone knowing what Havok is actually is capable of.
I mostly just modeled and textured myself. Animation was something i did if i got around to it, but i never got the hang of it. To this date i still cant make a consistent stair walking animation.
If you use Biped, you can place footprint markers... then go from there.
I haven't tried on stairs though.. I suppose in some games, it doesn't matter as the Foot IK is there and they just use the regular run or walk anims.