I had a VP150 above and a VP100 below a Samsung 61" DLP. The VP100 below fitted the stands and the VP150 was in an Omnimount above the TV.
Although different than the setup you are asking, just as a reference, I have to tell you that dual center channels, above and below the screen are really good for imaging right on the screen center.
As a VP100 owner, and understanding that you mention a Large projection screen, maybe you want to go for two VP150, or dual bookshelves carefully placed, depending on the size of your screen, which is on your mind already by using dual M22.
There is a lot of examples on the Axiom board to look into. From placement on the sides of the screen, or behind the screen, above and below. Send more details of the size of the room and screen and I am sure some of the HT guys will jump with a good example of what has been done with similar rooms.