I've just bought some muffs, but had I not, I think I'd get these. I'm still a bit undecided on the muffs- keep my hands warmish, but they were a pig to fit and need re-adjusting evey few rides (otherwise they foul the levers). I leave them on the bike too, but luckily so far no one has tampered with them. If they do go walkies/cause me problems, I think I'll invest in a pair of these.
As to them being dangerous, broken fingers perhaps, but I can't imagine theyd stop me being thrown off. If they were that bad; MCN would of run a scare story half a dozen times on the subject by now if they were.
