Well, A frame type needs at least 2 A-s, or even 3, which gonna move them toward the heave ones.
BTW, I came up with another imaginable or real pyramid drawbacks: the upper part of the zipper is over the sleeping area. Therefore, because every well protected zipper leaks under the right conditions, you gonna get wet. And that is true for all tent types having the entrance over part of the sleeping area, just matter of time.