I am following your thread and have the opposite question. I am just finishing up a PT-20 trainer kit. There is an option to include the ailerons or lock them. The ailerons are to installed, but the servo is left out and the ailerons are fixed in a neutral position. The servo can be installed and the lock removed at any time.  I have zero hours of flying time and intend to start to learn. Would it be better to go ahead and install the servo when I start or go ahead and learn as a three channel plane?

Thanks for your advice

Jim