Alright, now that I am home after 9 hours of driving. To answer your question the best I can I will have to go to the beginning of why differential is used and what it fixes. You may be aware of some or all of this so please bear with me as I think this will be good info for others as well.

Differential and tip stalls. We know that a " tip stall " is nothing more then a wing that stalls but having the tips stall before the inboard section of the wing. This is a situation that we just never want. Stalls are created when the AOA of the wing gets increased to the point of air separation. Having ailerons with more cord at the tip then the root, when aileron input is applied will have the tip effectively at a higher AOA then the inboard part of the aileron. This can promote the tip to stall especially if flying slowly or if the wing is already at a high AOA such as a steep turn. Aileron differential would reduce the aileron movement in the down position thus helping to not exceed the critical AOA. Since the 1960's it has been common practice on pattern airplanes to reduce the aileron cord at the tip. Benefits of this hold true with any airplane.

Other benefits of differential. Scale airplanes such as the subject model or a Cub type airplane with long wings and barn door ailerons will suffer from adverse yaw when aileron is applied without differential. This is because the downward aileron creates more drag then the upward moving aileron. The downward is creating lift and lift is drag. By reducing the downward travel you are able to balance the drag between the two and eliminate the adverse yaw. If you go even farther you can introduce pro verse yaw which can help with coordinated turns.

When it comes to our aerobatic models we use differential to eliminate adverse yaw but that balance not only balances drag at each tip but it also balances lift lost and lift gained between the sides to eliminate a slight pitch up.