RE: DD control problems
850mA 3S LiPo running a 10A BEC. Should be good. If yo uare comfortable with balance and the other issues I am too. The only thing I have left is that yo uare powering the servos at 6.4V and this may be heating up the servos causing one to wimp out more than the other. The heat of the day being higher than previous flights may make this more noticeable.
I would still recommend that a normal NiMh battery be swapped out before tearing out the servos.