The rear wheel on my LHT (a few years old now) is doing fine. It's also an XT hub and Alex rim, 700c size. (The front wheel was totally destroyed by me when I ran into something). I've toured with at least 20kg on the rear rack, and been over some rough roads. I've also occasionally slid the rear wheel sideways when stopping on wet or slippery surfaces, on my commute. I know that that's the quickest way to wreck (or at least buckle) a wheel, but sometimes it's just fun. (And carrying my mate on the rear rack a short distance also caused no damage ;-) To the bike, at least).

I wouldn't worry about it dude. Just enjoy it and fix it if it ever does break.

I've carried around the weight of a few spokes all the time, and never needed one on this bike.

Cheers, and have a nice ride!