Sorry to keep offering low tech brushed motor observations to this otherwise state of the art thread, but While backing my Blade CP into mother earth at maybe 25mph I accidently broke the Axe tail motor mount that I recently installed and had a good reason to try something else. I went to the LHS to get parts and found the uH cnc dual motor conversion. I bought it, installed it, and flew it. IMO the geared Axe CP tail motor setup blows the dual Motor set up away in the quickness department. It's about 4g lighter than the micro Heli dual unit and quieter also. The only downside I discovered with the Axe conversion is that you lose a little main motor rpm when the tail is working hard.
Truglodite, if you are serious about adding some brushed dual motor data into your excellent fact matrix, I know where there is a barely used dual motor mount available cheap. I'm either going brushed DD or going back to the Axe motor until I get good enough to deserve brushless.