I don't use either, but I'm going to try both.  I've never been able to use just my thumbs, I like the dexterity of the thumb and forefinger..... not that I'm a great pilot, I just like to float around, but I still like the control of both digits on the stick.  I'm starting to get arthritis in my hands though and it hurts pretty bad sometimes so I'd really like to try something that doesn't make me hold on the radio *and* fly.  Maybe I'll just get me a "scooter" and build a shelf on that to lay my radio on and then I won't have to worry about it.