I fly with index finger and thumb... it was the way I was taught by one of the best pilots in the area at the time. I tired to use just my thumbs and he corrected me for a while until it felt natural. Now I feel it gives quite a bit more control and seems the best way for me. I've actually had other guys come up to me and tell me I should only be using my thumbs, (mostly the old skoolers) and I tell them that's the way I was taught and like best. But I would agree to do whatever your more comfortable with...