This tier's HC gear should last up until say 97-98, maybe replacing the cloak with level 100 intro blues from 99-100 normal dungeons, the equivalent of 450 blues atm.
As long as the NPC damage output is scaled to SoO LFR level, if not less like JF scaled down to 372 (Firelands noral was 378, HoT heroics were 378) rather than 384 of DS LFR. I'm all for challenge while leveling, I'm all for challenge in general, but leveling is just a monotonous task. If leveling was interesting, something we'll be able to see in the beta, then sure; add more challenges.