I have 2 sets of Flows on XT hubs. Like you said I bought each set for the price of one hope wheel.
the only XT hubs I have seen with knackered cups is where chronic lack of maintenance means water has sat in the hub for 6 to 9 months. I have replaced knackered cones and the balls on one of mine but the cup has still been fine even then.
It is soooo easy to maintain an XT hub. New cone 2.60, new balls about 1.50, unscrew it, clean it, regrease it, put everything back in, adjust it. 15 mins. Do that, give it a quick true and its good as new for another 6 months.
You have to seriously not give a **** about maintaining your bike, or ride it in rivers of mud to run any risk of corroding a cup with the seals and just enough grease in place. I am about your weight and I do a bit of jumping (badly) and I like hubs with a big flange because my engineer hat tells me that is better load spreading than concentrating it like on hope hubs etc.