Sounds like they're bitten with the same old hardware bug. The problem of course is that 422 may not be readily available from your source.
I've found something interesting, though. Playing around with my SonyBDP300 blue-ray player into the Flea I've been able to get display of below black (based on the THX optimizer pattern) by adjusting the brightness control on the player. You then have to recalibrate at the display or elsewhere, but it does seem to work with both Studio RGB and 444YCbCr. The Sony player has selectable settings for YCBCr, Studio RGB, and PCRGB for the HDMI output. Of course it won't show below black with PCRGB no matter what you do which is correct behavior, so this leads me to believe this is actually a viable workaround. The stipulation is that it seems to require a brightness control at the source.