-3% hit is pretty nice for tanking, in my experience. Death Knights who go Frost can spend three talent points to get the same benefit, though it only applies to melee hits. I went with the glyph, though, because I don't have a static group yet and most PUGs I run have well-geared tanks in them.
I don't know if it's one of my addons, but I get a GearScore on items now. Pretty nice when you need a quick view of someone's overall gear level. My Druid just passed 4000, which is pretty decent. Most tanks I've run with have around 4200. For comparison, someone who just hit level 80 and have mostly quest rewards and AH blues would be at around 2600-2800.
I've run heroics as a healer with tanks that had a GearScore of 4600, which was pretty boring because they were all Death Knights (Blood) and their selfheals was pretty much enough to sustain them, even on boss fights. An example was Krystallus in Halls of Stone Heroic. Our entire group, except the tank, got instagibbed on the petrify thing (first time there, I had no idea what to do to avoid it). I actually died three times on that boss fight and the only healing I got in on the tank was a Rejuvenation, Swiftmend and a NS-Regrowth, before I was shattered again. He took down that boss using mainly his own abilities. On a run like that, we probably could've done it all faster if I'd just gone Moonkin and backup healed once in a while. The -3% hit would've been nigh useless due to his insane avoidance.
I've also run heroics with tanks that had a GearScore of 2500. That was pretty interesting, because if I missed a heal they would die before I could get the next one off. On one of those tanks I'd most definitely have preferred -3% hit there as it would've given me a chance to get a second heal off before the guy crapped out.
If you run with a static group and you don't have a -hit bot, and the tank is gearing up, I'd probably go with the Starfall glyph as well. I use Starfall a lot and on large group pulls, popping Starfall and spamming Hurricane (with ~300 haste rating) spikes my DPS to around 3500 as opposed to 2000 on bosses and regular pulls. An increase in Starfall damage would probably add quite a lot of DPS to that, not to mention the reduces radius would make me less worried about having to watch where I'm standing.
Hate it when one of those stars fall on a distant group of mobs.
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