FWIW, here's how I see the releases in different formats:

BD: everything and the kitchen sink, hell yeah!

DVD5 downscale: still a must-have for visiting relatives and friends, lots of people still can't do HD. I'm hoping your 2.1 release gets the DVD5 treatment too.

AVCHD: Neither here nor there. Not as pretty or feature-rich as a BD and not as compatible as the DVD5. I don't see much point now that it's not the top video-quality tier for the DeEd anymore.

MKV: I actually still like this as a way to get the best-quality video without all the extra bulk from lossless soundtracks and (yes, I admit it) subtitles cluttering up the thing. Then again, I'd actually like a .264 download which would work just as well and would be even more bare-bones ;)

EDIT: Oh yeah, forgot. The point of AVCHD is people without BD-burners. I think this is a shrinking market, the media and burners have both been down to reasonable prices for a long time.