I'm training for a 50 mile race at the moment and I've just got a pair of Inov-8 race ultra 270's. I've done a fell race and a few training runs in them so far and I find them very comfortable, light, and as they've only got a 4mm drop, they're really un-clompy which is nice for a trail shoe. Also they're designed for people of the wide footed variety so they don't feel constrictive.