A flying buddy and I are kicking a speed design around that uses (among several other things) all flying stabilators as the only control surfaces. Our design is optimized to manage and vector the pressure wave generated by the main wing and direct it to the stabilators, so we can make use of the higher density airflow. That being said, we then modeled it on realflight and found it only marginally controlable (even though the horizontal tail is nearly 50% of an already very short wingspan) due to the minimal roll response to control input. Now that is sort of what we expected, and the whole purpose of this plane is to drop out of the stratosphere and make a level speed run across the field. If it takes 1000 feet to make a 180 degree turn, that's OK with us, but would obviously be unacceptable for a sport plane. However, stabilators are used as compliments to the regular flight control surfaces on many, if not all, modern jet fighter designs, and could certainly ne used in conjunction with normal aileron function ti help improve roll rate.