Is it still rolling by itself?
I suggest bringing down the exponential to 25%.
If you pull up to a 45 degree climb and roll inverted while still at a 45 and let go of the sticks, the nose should start to drop slightly. If it drops too fast it is nose heavy. If it begins to climb then it's tail heavy.
As far as the rolling, it does seem like your servos are doing something weird. Those servos aren't slowed down are they? I know my radio has the option of slowing down servos.
How did you set up the ailerons? Are they matched to each other by mixing or slaving? You might check out the ailerons on the bench while your throttle is at high (it doesn't have to be running).

If by improvements you are saying you fixed it then good job. What was happening?

They are both beautiful planes.

Tim