I've got a crossmax XL front which i got 2nd hand off the classifieds as I needed a 20mm bolt through wheel and wanted crossmax rims. Experience of the 20mm adapters is that they are very hard to get hold of! The wheel has been fine, though it's only had limited use.
I think I read on the forum (when researching the elusive adpaters), that the XL rear wheels had big wear issues with the freehub. Rear ones don't seem to come up very often 2nd hand, which suggests they've all died long ago. Getting Mavic parts does seem to be a nightmare. My LBS said Mavic were very difficult to deal with. I think there was a thread yesterday on earlier crossmax freehub issues.