I don't know if the OP is having a unique situation with his
MA2. My own observation is that the 340 firmware does cause
MA2 to bank in "Follow mode" if flying forward while yawing. My feeling is that this is a feature to make the turns coordinated. The benefit is that it reduces the turn radius and it allows more accurate flight around obstacles. I have a PPL and a part of training was learning to fly coordinated turns--"stepping on the ball," as we call it. With the former firmware,
MA2 turns were flat skids and could be quite wide. I noticed it could get closer to trees or buildings than desired.
I am sure the 340 firmware is designed to never bank so far in Follow mode that the gimbal will not be able to keep the horizon level. At least I've never seen it. The user manual has the maximum bank the
MA2 gimbal can handle.
Regarding the gimbal, it moves continuously while the
MA2 is in flight due to wind, turbulence, accel/decel, turns and more. My own feeling is that if Follow mode keeps the horizon level, and the turns are coordinated, then it is win-win.