I play tanking vanguard and we've been farming EC hm with guild for month or so. Have about 60% shield chance with 70% absorb + 10% defense.
1. Threat generation is way too low and DPS output is low, no complaints about survivability so far
2. Threat generation is too low, I have to keep taunt and mass taunt constantly on cd to be able to keep aggro on single target. multiple mob tanking pretty much impossibility if dps are not focusing their attacks. Survivability is a joke, reactive shield only grants 25% reduction where as JK and Shadow get 50%, Adrenaline rush heals only 10% eventhough tooltip says it should heal 15% and even that wouldn't be enough, i think 20-25% should be closer. Smoke grenade is good and seems to be helping more than other defensive cd's. DPS output is really bad in tanking specc. Using MOX parser, I've only gotten around 600dps, where as pure dps classes do 1700dps, that easily shows why threat management is too hard even with recent threat buffs. Further, vanguard tanks don't have any abilites that are classified as high threat abilities like JK tanks have at least.