I guess the other point I have to consider is that a horse that is bred on this hard country will be far more clever than a horse brought up on flat land.
I must admit I have been spoiled with the other horses I have ridden previous to getting Phoenix. The last horse I had was a QH x TB that I bred myself. He was raised on the hills. Comet was extraordinarily sure footed, mainly I think because he was very athletic. I remember getting into a situation that required him to pivot on his hind legs and leap up a bank at the same time which he did effortlessly. The problem was we were only in that tricky situation in the first place because he was such a pig and wouldn't listen and we had had a big fight. Anyway Comet is a whole other post.
My neighbour has QH's that are used for cattle work and also he has a trekking business. For years I have been the trekking guide and his little QH's just float over anything. But again they are all bred on that country and it is what they are used to . Phoenix does well given that she is young and inexperienced although I have not taken her out in the hills since the winter rain started. We have fallen over twice but it seems to shake me up more than it does her.
A girl friend of mine lost her young horse about four months ago. They had got to a particularly slippery piece of track, she got off to lead Dude but Dudes front legs slipped out from under him. He did the splitz with his front legs. He died in his paddock the next day and an autopsy showed he had torn his diaphragm. It gets a bit scary when that sort of thing happens. I guess it doesn't matter the breed because accidents can happen to anyone.