Originally Posted by J.C. Koto

I say this as someone who had a failure with the XT m770 freehub -- chances are you'll be perfectly fine. IMO the problem was a manufacturing/design problem and not related to weight.

My problems started as something like intermittent chain suck at the top of the cassette when I'd stop pedaling. The freehub wouldn't engage and it would continue to push the chain. Essentially became a fixed gear for a moment until the chain would slap the chainstay and the sudden jolt would "reset" the broken freehub pawl. Kept getting progressively worse until it just quit altogether. It was not rideable at this point.

If you want to check, periodically remove the rear wheel and turn the cassette by hand, listening to the "clicks" as the pawls go over the ratchet mechanism. It should sound and feel even. If it ever sounds uneven with intermittent obvious differences, or if it physically catches than releases you might have a burgeoning problem.

Knowing what I know now I'd say buy a 14mm allen wrench (to remove the freehub) now and just keep it with you, but otherwise ride the wheel if it seems problem-free. The reason for keeping the 14mm allen is because they're not common, and believe it or not, a shop might not have one, or at least not know where it is..