I think I would be one of those people, North Woods. I have a lot of trouble with muscle memory and mechanical/spatial things, and once I learn something, it is difficult for me to switch. Although I went from trigger shifters on a mountain bike to Ultegra with no issue, and shifting has always been intuitive to me, I had an embarrassing experiencing leading a ride a few years ago.I was sweeping the faster group and this younger woman, who was clearly very fit was lagging and as we neared the end of the ride, I realized she had no idea how to shift. She had bought the bike in the fall and this was one of her first rides the next spring. She could barely get up little rises. I only looked at her shifters and assumed they were Shimano... we stopped and I was trying to show her, when I saw the SRAM. I only remembered something about double tap, so I started playing around. I couldn't figure out if it was double tap to go up, down, or both, and having just one lever totally messed me up. Anyway, I apologized for being a bad leader and I was able to get the bike in a lower gear for her, by accident!