I'm about to have a go at remapping a slightly modified V2RR to take V3 maps (I have UTC, which is awesome, but V2's UV layout is subpar compared to V3's). As to what the slight modification is, there's a slight modification to the hip, so if anyone knows of a V2RR that takes V3 maps already in existence, that would be even better (and I'll just hand edit the hip UVs; I converted the hip FBMs this way and it wasn't all that difficult).

Short of that, if anyone who's already done a remapping has any pointers to speed up the process, that would be appreciated. In the meanwhile, I'll be trying a few practice runs at it (in Blender 2.42 RC3 if anyone's curious).