Yea, they were ruined for me by a set of cheap ones on my first moutain bike. They were hard to turn and then would slip out of gear unexpectedly. Blah. Now I'm looking at an internal gear hub and most come with grip-twisters so I might be stuck with one. I'll have to look for the good SRAM shifters on their internal hubs.

I agree with the strong support for bar-ends. They're very stable for keeping hands on the bars while riding. Really any shifter that can be converted to friction mode if need be. I've had to do that several times and it's an invaluable feature.