Florent,
I never balance my stabs. Using high torge digital servos take care all the problem. The stabs only put load on the servos when it on the ground. Inflight it pretty much balance itself.
Remember balance the stabs need add alot of nose weight. The plane can weight 2-3lbs heavier if balance the stabs.
I never had any problem with my F-15 and my other full elevator stabs.
This stabs balance issue has beed mention so many time. But haven't heard anybody mention either unbalance or balance stabs having problem.
Many Y/A twin F-18 successfully fly without balance the stabs.
I know some hate to see the stabs hanging down after turn off the RX or the digital giving the buzz sound.
But for me I don't mind. 3 pound is make a big different inflight.
So there is a choice to make here. My personal experience shoot for lighter weight.
Brg,
Tam