warrior tanking gemming and rotation
While I am sypathetic that you would like tank gearing/gemming/enchanting to be about more than stam...it's just not the way the game is current designed. Threat is controled almost exclusively through spec and rotation. The native threat stats on your gear are all that is needed. This includes hit and expertise. If you get a good item that has a lot of hit or expertise but a little less EH, keep it in case of "gimmick" fights but don't feel that you have to use it for some baseline level of hit/expertise. For instance, there are some credible reports that expertise is playing an important role in Sindragosa hardmodes (not so much in normal though) because she is one of the only ICC bosses that parry-haste. If you find yourself in that HM fight, switch to that expertise soft-capped set you have been holding onto for just that fight.
"he doens't need healing, he doesn't need healing, he doesn't nee-WHAOSHIT!wtf was that man!". Please stop leaning on TDR. -Teng