I have flown both versions of the SM F15 and my preferance is taileron only. Very simple setup and in my opinion has much better roll than the aileron version. We've actually added Ailevator to the aileron version to make the roll rate feel better. It really comes down to flaps. If you have a shorter field or less than a 20lb engine the flaps will help shorten takeoff by about 150 - 200 ft.

Todd