I did mass balance the stabs. It nearly cost me the model. In a blonde moment I added the lead and was so keen to see how it worked I just went out and flew. Of course I didnt factor C/G into things and the lead added made the model too tail heavy. Anyway the out come was one exciting flight and the decsion that no difference at all in flying feel was made by mass balancing. I wont do it on the one I am building now.
As for airbrake.
Just finished but have not flown with it yet.