I'm not sure if my explaination is entirly correct but noone else has said it yet (or at least said it in the same way) so i feel i should bring it to the table.

I can supply no specific maths to this but its seem to me that the acceleration from straight and level flight to maximum roll rate is dependent upon the torque supplied from the wings due to aileron deflection and the inertia of the aircraft. I don't think this was actually the original question but it does deal with the issue of weither putting servos in the wings will affect roll rate. It WILL affect acceleration into max roll rate but i very much doubt it will reduce it by anything that you could call noticable.

As for maximum roll rate, i think the best way to explain my point is to look at the 2 extreme conditions

Maximum roll torque will be at the initial situation with the aircraft in straight and level flight and ailerons at full deflection (for simplicity i'm going to assume that there is no lag in aileron movement). The aircraft will obviously begin to roll at this point accelerating at a rate dependent upon the torque from the wing and there inertia.

the other extreme is when the aircraft is at its maximum roll rate. in this situation it is easiest to visualise whats going on if you take a snapshop of the wing at a moment in time. If in this snapshot you could view the angle of attack of the wing due to its rotating movement through the air. In the following i'm talking about the 'upward' going wing with 'downward' going aileron. the combination of rotating wing (moving 'upward' in relation to forward speed) and forward speed will create an angle of attack that would appear to be negative. As roll rate increases the negative angle of attack will increase until the wing (with its increased camber due to down going aileron) will no longer create any lift at all. at this point there will be no rolling torque created any more and it is therefore impossible to roll any faster. In reality this point will not be reached as you will still need torque from the wings to overcome the drag caused by the wings hitting the airflow slightly flat side on. So at some point you will reach an equilibrium between the reducing torque from the wings and increasing drag and at this point you will have reached your maximum continuous roll rate.

when aileron is released the oppersite to the above takes place and the roll will stop and return the wings to zero (normal) angle of attack.

So the 2 main factors affepcting your max roll are forward airspeed and lift prduced by wings at maximum aileron deflection. weight should not have a contibuting factor.