They're very nice but they're only on at the moment because they're new. I get out twice a week on the
Ribble, perhaps three times some weeks so I don't use them every day. I'll be swapping over again soonishly as the 60mm are a bit too much to lug around when my focus is all about hill climbing but even then, they're not as 'heavy' as I thought they'd be.
I also have some Ksyrium Elites 2011 which are sturdier and more of an all rounder. Saying that there's no point being too overly worried about using the Planet Xs. They were, after all, cheaper than the Ksyriums.