We've got two cribbers - a pony and a ex-racing TB. They both still crib, but not nearly as much as they used to. The pony was so bad we couldn't get weight on him because he was so worried all the time he would crib even with his mouth full and lose all his food. The key with both of them was finding a routine they were happy with and letting them relax.
For the pony, it was just a matter of him realising coming in meant he would get fed, go for a ride and go back out again and once he worked out he wasn't going to be boxed up and driven to a show or stabled he calmed right down. He still cribs when stabled and tied (horribly when stabled) but not in the field any more so he's out 24/7. I think he's just a naturally stressy pony and having a more relaxed lifestyle really helped him.
The TB still cribs, even when he's chilled and falling asleep, he'll do it half-heartedly, but he doesn't do it obsessively any more, or to the point where he wouldn't interact with the other horses in the field. He had a collar on when he arrived but his cribbing drastically reduced after we started turning him out without the collar on, and he doesn't put quite so much effort into it any more either. *shrugs*
Every horse is different though, and their reasons for cribbing might be different. For ours, it was habit and a coping behaviour, which I think means they might never completely get rid of it. I think collars can work for some horses, if the discomfort bothers them more than the reason they crib in the first place, but for ours I think it would have been the wrong way to go.