My rides are usually pretty variable in terms of speed, pedestrians, lighting and exposure to vehicles so I'm adjusting brightness and angle of my headlights to suit the current situation. Having a mount that lets me tilt the lights up-down on the fly is key.
^I really like the thumb switch...
I've used the Fenix mount for a while and I like it. It secures nicely and I've never noticed any slipping or rattling at least in an urban setting, I don't do mountain biking so ymmv.
My one complaint would be that the rotation adjustment has defined 'clicks' instead of being smooth and...