What gems for high-threat tanking kit?

[Julian]

When it's my job to frontload threat on a mob in a raid encounter, and the tanking job at hand isn't that demanding mitigation-wise, am I better off:

1) socketing for +spell damage
2) socketing for +spell hit, up to the hit cap
3) socketing for +hit, up to the hit cap.

My guild is starting to get into encounters where this is going to be a reality, and I'm starting to work on a high-threat, lower-mitigation tanking kit, so I'm hoping somebody else has done the math on this one already.

To be honest, I'm not even positive what of our threat mechanics +spell hit versus +melee hit help us with.

[Karathos]

assumng you have the requisite defense and respective avoidance to hit uncrushable if necessary the next key would be +spell damage.

you can cap out max needed +melee hit at somewhere between 5.6 and 8.5% for paladins (they don't dual wield so their requirements are lower)

spell hit would help with resists, but a reasonably high percentage of our threat is completely reactive (dorvan has a thread about it elsewhere in the advanced forums if I remember correctly talking about where % of our threat comes from.)
so adding + spell damage is extremely solid.

one thing to consider would be +spell damage consumables and the +threat enchants along with optimizing your talents for all the +threat rather than +mitigation. (i.e. sanctity aura + ImpSotC) and going for the +spell damage thread for pants and +spell damage enchants on shoulders and other available locations.

consider that +spell damage will add directly to your threat and the other two alternatives will only help with resists (+spell hit) and misses (white damage threat from +melee hit).