I know this is an old thread but I have something to add. I have two brothers who's systems have had Denon's Audessy, Harman's auto-tune, and Pioneer's MCACC. I got to watch multiple movies with all three technologies' auto-tunings.
My choice is going to be Pioneer's MCACC. I've listened to various sound systems for audio and theater for years now and have heard some of the best setups at CES in the past and I have many THX rated movie theaters in Vegas to watch.
I know what sounds good and what sounds bad in my own opinion.
In each case where I didn't like the sound, my brothers were in total agreement.
My older brother owns the Denon receiver which was last year's model. We watched the newer of the Incredible Hulk movies. Denon's Audessy auto-tune was so soft, so lacking in dynamics and imaging that movies seemed lifeless compared to when it was switched off. My older brother doesn't use Denon's auto-tune now. He says it "kills the highs". Metal clinks and certain noises with high frequencies just sound, "wrong". I totally agreed. My older brother still owns the Denon receiver and is happy with it but not with Audessy.
My younger brother has been assembling a really really nice home theater for himself. He has a Sony Bravia DLP 60" screen that looks hella nice in his light-controlled living room. He's using Polk "dynamic balance" based speakers all around including in-wall and in-ceiling speakers and my 14-year old but powa-ful Cambridge Soundworks PSW1 (can still shake a house after all these years). I shouldn't have ever sold him that sub.
Anyway, 4 months ago he bought a Harman Kardon 7.1 receiver and then ran the auto-calibration. We popped in "Watchmen" on blu-ray putting thru the full HD audio sountrack. Although it sounded, "okay", it too seemed to share a similar problem with the Audessy auto-tune. Very laid back highs, overly soft sound and nothing seems to "jump out" at you. Dynamics aren't nearly as laid back as the Audessy auto-tune but Harman's just didn't sound "alive" like a soundtrack should sound. We ran backwards on the Watchmen bluray and played back sections with the auto-tune engaged and then disengaged. It simply sounded BETTER when turned 'off'. Bummer.
My younger brother and I both observed the same thing. My brother did some more research and decided to order a (non-elite) Pioneer model in late November and configured everything and ran Pioneer's auto-tune.
We watch GI Joe this time then the newer Harry Potter bluray release. The sound was MUCH MUCH better. Dynamics were much better. While not perfectly 3-dimensional, it had WAY more depth. Sounds like broken glass and metal "tinkles" sound correct instead of tinny or "wrong" like on the other receivers. For the first time after two other receivers being heard by me, the auto-tune actually sounded BETTER turned 'on' rather than better when 'off'. Pioneer's auto-tune allows you to change ANY setting it's automatically done. My brother hasn't changed a thing and left it on "auto".
I don't have any scientifically fancy schmanchy test gear but I'm pretty confident what I heard was spot on and confirmed by at least one other person who I know are technically inclined.
My opinion, (for what it's worth) I only seem to find acceptable quality in 1 out of 3. And the 1 which I like actually DOES make the sound 'better' and more realistic for both music and movies. I haven't been able to get a full and practical session with Yamaha's auto-tune, so I can't comment or give an opinion on that one.