We didn't have SoV (SoCor) so we were stuck with SoR, which as you know, was an absolute failure for a seal. Offtanking or addtanking wasn't a problem as a paladin, maintanking was. Had we got access to such a potent DoT and Judgement effect, i dare say TPS wouldn't have been such an issue for us. For horde tankadins, T5 was fine. Then in T6, TPS seemed to plummet. I'm guessing this was down to higher avoidance, thus leading to less threat generated by SA (although on Bloodboil, stacking the DoT up to 20+ [i personally hit 31 stacks before the damage overwhelmed me] and then the mana-regain threat from SA was keeping me at 3K+ TPS). I am still curious if BoSanc generates any threat at all from the mana regain (i dare say it does, but i've never really tested or noticed it).
@ Daez: 40.5K HP is fairly attainable. There's times for mitigation gearing, and times for HP gearing. I personally run with HP gearing all the time. It might be because i like to PvP a lot as well, but it helps with Sarth trash adds, as well as Patchwerk. Once 3.1 hits, i'll be speccing back into Deflection as well so my Mitigation/avoidance will rise substantially, and based on the "some stuff's being reduced in ranks" theory, i expect we might see some more talents, possibly mitigation.
It all depends on playstyle really. I prefer the high-hp approach, while other's prefer avoidance gearing. Something else my gearing and talent choice (HotC for example, although that was more the help buff the raid's DPS, rather than buffing my own threat) brings to the table is high threat as well. I've made strength (more AP and BV), hit, and stam (thus translating to SP) a point in my choices, and this generally leads to higher TPS output. If i could find another slot for a 24stam gem, i'd be at 33K unbuffed, so 40.5K raid buffed isn't really that difficult. If you wanna talk about HP, talk about the 80K HP druid i saw in AV a few weeks ago =P
he prolly had the av buff as well :> and no i wont start to present the calculations (which prolly arent fully correct anyway) for this one