Problem solved (well, the Warp3Ddemos work so I thought I'd post with what I did asap before anything else happens ;-) )
Checked out my libs dir and I had the following in Warp3D:
GFXDrivers
W3D_CyberGFX4.library - 40,292 bytes - version 4.2
W3D_CyberGFX4_PPC.library - 16,128 bytes - version 4.0
W3DPicasso96.library - 38,664 bytes - version 4.2
W3DPicasso96_PPC.library - 20,508 bytes - version 4.2
HWDrivers
W3DPermedia2.library - 579,708 bytes - version 4.2
W3D_Permedia2_PPC.library - 502,980 bytes - version 4.2
Now, in my backup (created as soon as the BPPC and BVision were installed and working) I had:
GFXDrivers
W3D_CyberGFX4.library - 38,996 bytes - version 4.0
W3D_CyberGFX4_PPC.library - 15,412 bytes - version 4.0
HWDrivers
W3DPermedia2.library - 93,120 bytes - version 4.31
W3D_Permedia2_PPC.library - 396,812 bytes - version 4.2
Notice the difference? Mainly in the filesizes of the HWDrivers dir being ~700,000 missing
God knows what happened (or what installation, or me getting libs from Karlos to try Quake stuff...), but it seems to be happy now :-)