I don't know anything about the XT hubs no longer being "good enough" for touring based on the flange material... that's a new one for me. That said, there was a bad run of XT hubs where the freewheel was cracking and as far as I know, there is no way to distinguish the good from the bad; it was a problem for a while and newer stock should be safe... but, you never know what you are buying, especially from an online vender.

LX is not lower in the hierarchy, SLX is. The LX line has moved to a touring/commuting category all it's own and is no longer considered part of the mtb lineup. Unfortunately, the LX line up is being pushed more in Europe and can be hard to find parts in the US (and presumably, Canada).

Handspun/QBP used to make the LX/Mavic 719 wheels for touring. They currently build an XT paired with the DT Swiss touring rim (TK 540). They use the XT hub with the six point connection for a rotor and not center-lock, so maybe that's the dividing line?

Quality Wheels Pavement Series 6 Rear Wheel 700c Shimano XT / Mavic A719 - Modern Bike
Quality Wheels Pavement Series 6 Front Wheel 700c Shimano XT / Mavic A719 - Modern Bike

My current rear wheel is holding up well for my 200# of excess... although I did need to true it a bit a couple of times.
http://www.treefortbikes.com/product...29er-Rear.html

I generally like the QBP/Quality Wheels/ Handspun but they recently changed their website which annoys me, because the old site actually listed their product numbers and now I'd have to d/l the qbp catalog to figure that out.