I've read of bearing/cup/cone troubles only on the revised XT hubs, which is logical since they use smaller 3/16" balls (like front hubs) to accommodate the 14mm diameter Al axle (vs the old 10mm steel axle), in a hub shell with the same external dimensions. While the axle is stiffer and less likely to bend (good for jumping off rocks), smaller bearings wear faster for a given load, and are more susceptible to damage from grit/foreign contaminants (bad for tourists).

This is the first time I've read of a newer XT freewheel failure (well, outside of mtbr.com, where they manage to break everything). Troubling news since Deore-LX-XT-XTR freewheels were highly reliable (and largely interchangeable) for a decade or more.

I've gotten 15-20K miles on a couple XT rear hubs, fronts go even longer. I recall retiring a FH-M750 at 22,000 miles - a groove had worn into the cup, and it had begun to get a little rough. 750 hubs cost ~50 bux only a few years ago, so I pitched it.

I had another FH-M750 die at about 15,000 miles, due to user error. I washed the bike with hose, blasted the cassette area clean, parked bike for 2-3 days. When I took it out the rear hub was partly seized. Inspection revealed corroded balls, pitted cups and cones. I repacked it and tried riding it, it was still rough. Lesson learned - never wash bike with hose, never immerse hub in water, repack bearings immediately if this happens. Shimano hub seals are not waterproof. They'll resist rain, and that's their limit.