I find having my boat loaded even, and flat on the water, with towers centered, gives me the best performance, especially pivotation. But even weight distribution is more important, and as long as you do that reasonably well, you should be all right.
One reason you see small cats with the frames forward, for instance, is to get the weight centered. Of course there are other reasons, like being able to grab some green water on the down stream side of a hole( that's why P.N.W. crazy fuckers do that ALL the time
), also good reasons to run a frame aft, like having room for four paddlers, or giving your passengers some space.