Anywhere from really no real advantage at all to nice indeed. The Senior has substancial dihedral and the simple act of adding ailerons will result in rather unresponsive roll control which work just OK. Now if you choose to reduce the dihedral down to about two or three degrees say about one third of stock then you will have a delightful improvement and an airplane of an entirely different character.

Ailerons can be done in two basic ways. The first is fairly simple and involves sawing off the trailing edge till you have about a quarter inch blunt edges then hinge on say one and a half inch aileron stock the full span of the wing. This will result in strip ailerons that protrude behind the original trailing edge about an inch so they must stop short of the fuselage. Torque rods just as in most trainers is inlaid to the center of the wing bottom and a servo added forward with short pushrods.

If you choose to use barndoor ailerons it involves more work but is nicer looking and quite responsive. A false spar is added to have something to hinge to. These ailerons can be of much wider chord. Two servos and mounts are added one for each aileron.

I,ve done a number of both methods and the barndoor type is my favorite. Here is a picture of mine that you can see the structure that was added and servo arrangement:

John