I'd take the MC-1. Of course, I have an MC-8.

(Go check out Lexicon's site for all the reviews. Ecoustics has a bunch of reviews too.)
The Lexicon has Logic 7 and multiple crossovers. Neither of the other two do.
IMO, until DPL IIx becomes widespread (and comparisons made), Logic 7 is the pinnacle for movie soundtrack processing.
V4 of the MC-1 does support THX Surround EX and DTS-ES (by allowing overlay of EX processing over DTS).
The Integra is not software upgradeable and doesn't have, and never will have DPL IIx. Look around for threads on the Ref 50. I have seen quite a few people post about the high frequency whine the unit has.