Mmmm, I'm not exactly sure what you are asking (prolly my fault), but yes the lens is simply an add on. You will need vertical stretch, but it's hard for me to imagine that won't be standard issue with the pedigree of PJs you're looking at.
No offense meant here, but this is exactly what the layman thinks. The horiz center speaker came about purely as an aesthetic compromise. They have become so entirely ubiquitous, that the layman now believes it to be at least necessary if not simply superior.
If a horiz layout was indeed superior, then all of our speakers would be horizontal. The first issue with the most typical horiz MTM is lobing, since two drivers are playing the exact same thing, and once you are offaxis, the interference will create certain sets of boosts and cancellations depending on the offaxis angle. Why do they have two drivers then? To be able to effectively produce enough sound at those frequencies.
There are better ways of designing a center speaker. You can have a WTMW. The dedicated midrange woofer lets the speaker xover the woofers low enough where lobing is no longer detectable to us.
Another solution is the coaxial, which again implies a dedicated midrange (that doesn't try to reproduce bass). One of the better compromises with this design is that it can be shorter of a speaker (no tweeter above mid).
So, let's come full circle here. Three identical speakers, vertically arrayed, all on the same height gives you these advantages:
-even height of all drivers for the best panning
-the best acoustic match truly possible
-no lobing issues
-very often better power handling
And the above is when I assume a center channel speaker is "properly" placed. However, it usually isn't. Mine isn't.
Read this excellent article (and the follow up article, basically saying that horiz center speakers aren't really that bad as long as you aren't crazy offaxis). Of course the second article doesn't go so far as to say that vertical isn't better. The first article is written by Chris Seymour, that's right, the owner of Seymour screens.
http://www.audioholics.com/education/loudspeaker-basics/vertical-vs-horizontal-speaker-designs
By most/all accounts, negligible. It's the
audiophiles who really love this screen, so that should definitely say something about its AT capability. Video, that's where you may find a more differing opinion. Check out rmk's system; he went from a Stewart to Seymour recently. I also recommend checking out both basspig's and mperfct's systems as well, both with Seymour, and both of those with anamorphic setups.
http://forums.audioholics.com/forums/showthread.php?t=36461&page=80
You bring up an excellent point, with the full 1080p. Another thing you get is the maximum capability of the PJs brightness, since black bars with regular setups are wasting about 1/4 of their power on black bars.
However, your FL will be lower when using the lens with anamorphic, since the light power is now spread out more. Detractors of these setups would bring up the most obvious point in that you have to distort the image two times, once by using the vertical stretch, and then of course stretching again horizontally with the lens. This is why you might see an expert like BMX saying that if you go this route, get the checkbook out, because you don't want to skimp on glass. Is it worth the money? Individual answer. For the person who might afford a 65" plasma, he could instead get an Epson 8500 with a Focupix or Carada screen for even less money. Once we're getting closer to 5 digit budgets for video, ok sure . . . .
Since you pick my brain a little more, I think the truly best implementation with automasking would be to have masking for BOTH horiz and vert. Then you can choose any darn size for any darn AR at any time. Now, this requires zooming/refocusing, and this is a can of worms I'm not getting into now. Anyways, have you seen The Dark Knight?
You are whetting my appetite a bit with this anamorphic thing. I can rather easily alter my screen for 2.35 AR, my audio would be significantly improved my further placing the center speaker away from the midbass boosts of the floor (even if acoustically treated), and I can scoot my seating even closer, hehe.