Up until 2010 there wasn't much difference physically between XT and LX, or even Deore hubs for that matter. The parts were interchangeable. Supposedly the bearing cup and cone are made of a harder material on XT and LX, which theoretically translates to longer hub life.
The latest XT hub is internally different from the way these hubs have been made for the past 20 years. They've gone from a 10x1.0mm steel axle to (i believe) a 14mm diameter Al axle with end caps, and the ball bearings went from loose 1/4" to caged 3/16". They did this to make the axle more resistant to bending, save some weight, and perhaps to market the hub better.. However, reduced ball diameter sounds like a bad idea, since generally they don't roll as well or last as long. I've read a few reports of new XT freehubs dying after very low mileage due to the bearings. They should have put some decent cartridge bearing in instead, then you could replace them if necessary. You can't replace the pressed-in bearing race (cup), which is usually the life-limiting component of this series of hubs barring misuse, or rust from immersion (the seal is water resistant only).
So, anyway, I'd use older (<770 series) XT freehubs or just use LX or Deore.
IIRC LX is now obsolete for 2 years, replaced by SLX.
Besides Shimano, DT hubs are nice and not too expensive, and Hope hubs are really worth a look but harder to find.
Front hubs will normally outlast rears by about 3:1 due to wheel weight distribution. Nearly any front hub will work well for touring purpose. All hubs and rims (and every other bike part) are ultimately consumable, in that if you ride >3K miles a year you'll experience everything ultimately wearing out or breaking. Even frames and those mythical "lifetime" Brooks saddles.