In reply to sean1: 5mm xsedge is probably the most durable sole la sportiva have on offer in my opinion. I had it on my shoes for almost 14 months of heavy use both indoors and out (mainly slate and rhyolite) and by heavy use I mean 4 sessions a week indoors and long days out at the weekends.Only now I'm noticing that the edges don't offer as much help when edging as they used to. I guess that the 4mm xgrip might be slightly more sensitive but I couldn't really tell the difference, also it didn't take abuse as well as xsedge.