Quite a few people at the yard use them, I know they are made of a different metal and are a different shape to "normal" bits, but what difference do they make when riding the horse?
I have a KK bit which my horse seems to really like - I bought it on advice from a bit hire company www.thesaddleryshop.co.uk as my horse was fussy in the mouth and I wanted the kindest bit for him. There is some info on that and other similar websites.
He definitely seemed happier in it. I believe that the shape is more forgiving to the horses tounge, and in my case my boy has quite a large tounge so that made sense.
Ive tried loads of different bits including kk, neue schule, myler etc etc and although I think at first hes better in x, he actually isnt. Im currently riding in a kk but lunging with a bit that cost about a tenner (2 different bridles for convenience) and I cant see any difference in either. My horse does have a tongue issue though.