Geno, I think that Gena was just suggesting that you use a smaller screen that would leave enough room underneath it to fit taller speakers, such as M60s.
Identical vertical speakers across the front are my suggestion, but if you can't arrange the game players to leave the center open, then use a horizontal center as you describe. There's no "ideal" speaker height; if the tweeters point to the ears that's the major factor. Also, the woofer cones should if possible be at unequal distances from the floor, front wall and side wall.
