you're not limited by biped in terms of bone amount - it let's you attach dummies, or entire bone hierachies to any of it's joints. the bad thing is that you cannot do parameter wiring to e.g. read biped body part rotation and accordingly position a deformation helper bone. biped doesn't seem to expose that kind of…
that tip about using different rigs/skinning setups on the same character is interesting. do you swap out these models ingame from one frame to the next - does the mesh itself have to be swapped out or is only the skinning information replaced? as long as artists are not allowed to use corrective morphs, this seems to be a…