RE: Mehcanical Aileron Differential
Personally, I think you're over-analyzing the situation.
If you bought a new car, would you put new tires on it before you drove it because you think it needs a different type of tire tread? Probably not. You would drive the car and more than likely decide that the current tires work well enough.
It's the same thing here.
Build the kit according to plan and fly it. More than likely you'll be pleased with it the way it is.