All the tests hold true regardless of bit depth.
If you want more confusion, consider that the new RGB(A) formats are
planar; you can't call
ConvertBits(x) on an RGB32 clip, you must call
ConvertToPlanarRGBA first. I have posted a utilities script, called
Utils-r41.avsi, that (among other things) hides this complexity behind
To16bit and
ToHibit(bits)