In the past, Shimano has claimed borozon-hardening on only its premium lines, specifically XT, XTR, Ultegra and DA. Lately their product descriptions make no mention of it, so perhaps its been discontinued, expanded to all products, or they've decided it's an ineffective marketing point and chose to not advertise it. Maybe the limited success of third-party marketing of "ceramic" bearings has effected their decision to use or advertise borozon (which is a ceramic too).

Although borozon has been used successfully for years in mining and tooling applications, I'm not sure the benefits are significant in the case of MTB hubs used for touring. To most cyclists it's simply pixie dust that helps them justify paying 100% more for a hub they want that's probably only 1% better.

I've got 7,000 miles on a non-borozon Deore hub so far, with no sign of wear. My best performance on XT hubs are 22,000 miles, but they started developing an erosion track at about ~17,000. Ask me again in 2 years and I'll be able to make a more informed comment on Deore vs XT hub bearing race wear.