No I haven't but I played pool for alot of years before they came out(to my knowledge anyway) and learned to play without one. I think people should think about whether they can reach a shot or not when deciding where to leave whitey and if their opponent leaves them a shot they can't reach maybe that's part of the safe. I certainly consider if I can reach a shot while running out. I struggle with a bad lower back and I'm STILL against it. I know that only a rare few would side with me here but that's just how I feel. Play lefty, behind your back or with a bridge or don't shoot the shot. Again though, I'm not trying to fight the world, I know they are here to stay. I just don't allow them against me for my money and that's my choice. It's kindof cheating IMO.
I'm ok with Jump cues(on some very small level i think they are similiar items and just assumed someone would bring it up) but understand why some folks are against them too. People are entitled to their opinion.