big screen - two channel system enough for dialog?

thanks for all the responses so far. i pose the question now because I am building this room from the ground up and am trying to figure out how much wire/conduit to lay, the general layout, and of course budget. from what i have read, there are lots of people who think 2 channel is not only better value, but superior in many ways.

i just worry about the separation of my mains when it comes to dialog as I will be using a pretty large screen and I don't want it to be high up. So that leaves mains spread apart which means they'll have to be well out into the room.

one solution i was thinking of was to use Klipschorns (i am one of those high efficiency plus low power tube kinda guys) in the corners. this would allow my big screen in the middle, at almost any height, maybe with a couple of subs underneath, and the horns off into the corner. This would leave the floor clear, a big bonus since I have small kids.

Zd542, I totally take your comment about centers being too small in many cases. the HT systems I have heard often have this problem, and I think quality two channel might even be better in this case as imaging might be better.

I know I can go with the trial and error method, just want to avoid tearing up walls, repainting, etc if I can.

20' diagonal screen seemed to me the size in Lowes theatres for sub-100 people audience:-)

If you are okay with the bass limitations of the K-horns, then a natural choice for the center channel is a single Cornwall or maybe a pair of Heresys.

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Marakanetz, I could seat at least two additional rows of eight people in my theater, but the people in the second and third rows would not be able to see over the heads of the people in the front row. The second and third rows would not be elevated. Therefore, I keep it to eight people in one row so everyone has a great seat. For kids movies I've had as many as 25 kids over for a movie...most of them sat on the floor and they loved it.

My theater is not a dedicated theater, it is also my living room and my music listening room.
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I've gone through 3 or 4 center speakers, and was never satisfied with any of them, due to their inability to render the human voice as well as my L/R tower speakers. I did not find any improvement in dialog intelligibility when using a center speaker. The biggest drawback with all of the speakers I tried was that they could not reproduce the baritone quality of male voices, no matter what crossover settings I tried. I finally have just decided to use the phantom setting with my L/R mains.