Standard wisdom has it that ideally the FC should be mounted at the center of the vehicle.
Just to mention how inaccurate most people's interpretation of that is, it should really be that the accel chip (not gyro chip, not FC center) is mounted at the center of rotation (all 3 dimensions). People don't take into account that the accel chip is not at the center of the FC. They also don't take vertical position of FC or off center weight of battery into account.
The bottom line is that having the FC a little off of lateral center will only be noticeable in extended fast pirouettes where the centrifugal force will make down point a little outward and cause slight drunken behavior during and after the pirouette.