I like Lexicon but probably not in the same purist sense that many look at it - they have the only truly upgradeable processor, and that's because they offer generous tradein allowances on legacy processors when they come out with something new. That's the only way that "upgradeable" means anything to me.
I don't agree with the sentiment that all surround processors basically sound the same and that "good enough" will do. True if you're really avid about your music but just enjoy movies. Lexicon uses their own proprietary Logic7 surround algorithms, so it's also not true that they're all based on the same technology. I owned the MC-1 for a couple years and it's definitely not the last word in 2-channel reproduction, but it's a real nice product IMO, and you can currently get them for less than $2500 used which is an excellent deal in my opinion. Even if you ultimately add a dedicated preamp for music (a good suggestion if you can ultimately swing it), it's not overkill for HT-only. I'd recommend that you find out whether the MC-1 you were to purchase used has already been traded in (Lexicon could tell you from the serial #) because each unit is only valid on trade in a single time.
A lot of people who buy the Lexicon processor want to (and do) use the Music7 surround logic to do multi-channel reproduction from 2-channel sources. If that holds no interest to you, you'll be missing what many consider to be a major selling point of the Lexicon (including JGH, for what it's worth). I haven't used any of the other processors you mention, so my comments are in comparison, but are based on owning a succession of the Lexicon processors (on the MC-12 now). -Kirk