But, since I've started my contract work in Boston, I have had to learn another 3ds Max rig called the CAT rig. Same type of thing. A pre-made rig that can easily be set up with any character you have. It also has some special tools that comes with it, that are specific to that rig.
I have to say, for what I've been working on, I think I like the biped rig better. The layer system makes more sense to me personally. It tends to blend better and has the magnet tool that can pickup a pose from the layer beneath. And for mocap cleanup, the different key types can make things a lot easier. Plus, the biped was built in a way that allowed you to use Fk and Ik at the same time in a way. I don't think it was complete Fk, but you could definitely move it like an Fk if you rotated a certain way. Though, the CAT rig is nice for people who like to work completely in FK or IK. It has a controller that lets you switch between the 2. Which is actually how it was in Maya for me, so its not like I'm not used to that.
The only thing that I don't really like about biped is that the curve editor makes no sense to me. Its got its own special editor but its hard sometimes to get it to do what you want. And, at least with mocap, it can be a little buggy. I've had my issues with it. The CAT rig uses the nice, normal curve editor that does was you think its doing. That is the one thing about biped that drives me nuts.
So, in conclusion, guess the CAT rig just needs some more exploring. But as of right now, for me personally, I like Biped.