Mine don't seem to last longer than about 8 months before the plastic wears, has anyone found any suitable alternatives which are hard wearing, fit and shift well?

Gareth

Do a search. There was a long discussion on this a couple of months ago. I use XO's with sealed bearings for the one wheel, which prolongs the seize on that one

I've got the BBB ones (for my X9, but I think there's an X0 version), seem to work fine, sealed roller bearings in them. The outer plates gummed up a bit after some very muddy and wet rides but nothing major, took minutes to sort. I've not had them for long enough to really recommend, but they're cheap-ish and they've lasted decently so far.

I've been using the KCNC jockey wheels since January. They're aluminium rather than plastic and I haven't noticed any wear yet.

I think the BBB ones fit X7/9/0, with variations in the adaptors supplied.