"...V4 textures; I am fairly certain the UVmap is exactly the same."

Unfortunately it isn't. The mesh is the same, but the mapping is quite different.

I just created myself an 17K LOD version of M4 by transferring the M4 bodyshape as a morph over from V4.

And I had to convert the M4 texture to V4 to fit the (V4 mapped) new LOD mesh.

BTW, there is NO M4toM3 hybrid figure included.

Also UTC-2 can't convert D3 or M3's genital textures over to M4.