Eddie,
Are you familiar with the Vertigo? I would think that the Vertigo's vane setup would translate very well to your Rig. In the construction article, the only short moment problem was with yaw. In pitch and roll you also have gravity "helping". If the moment of the vanes was say 6" below the C.G., Consider a 30 degree right roll vane input. This would would cause the thrust vector to intersect the horizontal C.G. "plane" of your Rig 3" to the left of centerline. To get an idea of how fast a roll rate that is, put your Rig on a balancer that is 3" left of center and let the right wing drop. This will be pretty fast. Of course gravity will help the most when the Rig is horizontal (0 degree bank). If you tried to correct from a 90 degree bank (you'd be falling almost straight down if this happened, you'd also be at full power and accelerating horizontally) gravity would not help much, but aero dynamic forces would. The same will be true for pitch. With yaw, the assymetrical thrust will not have gravity to help, so yaw will be completely limited by the short moment arm.

The vanes don't add much weight, so they could be used in conjuction with your rotor system. Tests could be made at altitude by turning the rotors off in mid air. If the vane setup seems promising to you at that point, You could tweak the vane's authority while still having the rotors to "fall" back on. The risk of testing should be minimal while the possible benifits are many. It would look more like a jet without all those twirly bits on it too