Hmm, the danger of these forums is that people's personal experiences and opinions are not necessarily particularly valid when it comes to the truth! Mine, though, is no different, so rather than say "they're great" or "they're rubbish" here is some food for thought.
I made a poor-man's pantin (out of a croll & webbing) in the mid-nineties during an expedition to the Picos with some Spanish cavers. It was fairly routine in europe at the time to do this sort of thing. Finally Petzl caught up with us!
In my opinion, if you're an occasional vertical caver (which is likely if you're only active in South Wales?) then I wouldn't bother. But, if you do consider yourself to be a vertical caver then you obviously realise that the pantin has become pretty indispensable by now. However, I believe that you need to learn to cope without one in all situations before you consider buying one as they can be slightly tricky to master. In fact, I refuse (in a nice way!) to let anyone I train touch a pantin until they've been dangling around for a while as once you get used to them it's difficult to let go. Kind of like allowing a baby Jedi to play with a lightsaber before they have mastered the skill of removing maiden's knickers from afar using the force......
They don't always feed through (mud, require a few metres of rope below to give a bit of weight etc....), need to be taken off below deviations, need to be removed for general caving to prevent snaggage/damage/filling with mud. But they come into their own on long pitches, tight pitches, technical pitches, passing obstacles with heavy bags, etc... I found it to be a near life-saver in the past when I did my knee in a long way from surface: with a standard foot loop arrangement I'd have been a lot more screwed.
In Llanelli Quarry Pot beware of little problems that they don't mention in the books: accidentally attaching pantin to the donkey's dick/haul cord when it's hanging off your harness & ratcheting your foot up into your arse, for example! I have seen people get into the highly comical position of a flying angel/chocolate starfish (!) when they've neglected to remove their pantin at rebelays. For this alone I think they're awesome bits of gear!
So in summary I'm all in favour of them but not for every situation. And surely you've gotta be able to avoid using trainers underground when you're on the ropes? Can't be a good idea.....
