I think Ken's on the right track. It really depends A LOT on the room. I think it would be important to keep separation between the center and the mains, and also to have a fairly focused, coherent image for the center. Remember that a previous generation VP150 was a different array (MTMTM), which was abandoned in favor of the current configuration (TMMMT). That was a relatively subtle change compared to what you're considering, but was obviously quite important in Axiom's analysis. More drivers splattered all over the place is not necessarily "better".
