I've since tested with a Vero 4K+ to allow 3D and HDR playback. Here are some more specific results using the Vero:
Default Settings (YCbCr, limited) give me ability to adjust Black Level correctly, but Contrast doesn't affect white and I can see up to 252/253.
YCbCr and full give me clipped BtB and WtW at limited levels. I think this is the better option, but I don't know if I'm losing info due to conversions...
I can check the output with RGB, but most of what I've read says YCbCr is best from this box. Of course I've also read so many conflicting ideas that I don't know what to think anymore.