Well I only have some pieces of gear and try to make them work the best as I can, got a great health pool, nice avoidance, cause we're progressing on naxx25 with the guild and I think it makes more easy the job for the healers, but last night i was having some troubles with threath ... so i decided to regem ... and came up with this :
YOu have way over geared for expertise, your not even at the Defense cap of 540 atm and your health at 25k is low for 25 man Naxx you need to get both of thsoe things up jsut get your expertise to 26 and you should be ok.
I'm only seeing 28.3k HP unbuffed on the chardev myself, but regardless, that's perfectly fine.
Threat wise, you're right at the hit cap, which is perfect. You're sitting at 46 expertise and around a thousand SBV, so your threat will definitely be great. Only things I can suggest is a talent-change, and that would be to take 3 points out of shield spec and move them to focused rage, and to change your glove enchant from expertise to Armsman.
You'll still want to maintain some sort of EH and avoidance focused sets, however, on top of the threat set. But that's another issue.