TL/DR: My tanks feel useless: either the group is great and don't need a tank, or the group is terrible and my dps isn't high enough to help.
I have never looked into a tank that can do some decent dps, most of my tanks add utility and either shields/healing to the group in addition to buffs and boss debuffs. But after a 90 minute Spindle 1 Vet last night I began to wish I could have done more DPS on the Whisperer, which literally took 40 minutes. I was running a DK tank and I was popping war horn, keeping the boss taunted/breached/maimed, keeping weapon buff up on group and giving the whole group 10k shields every 3 seconds. One DPS did not understand the boss's spit mechanic and accused me of not holding aggro even though I had explained the fight. He laughed at me and told me I was a newb and an idiot and then disbanded half way through the fight. The healer and other dps died repeatedly and I kept rezzing them. I never died during this fight. But my own dps is pathetic.. something like 2K I was thinking if I could get it to 10K-15K then these long dungeons might get faster. Most of my tanks are nigh well unkillable in any vet 4-man. I almost never die under any circumstances. If I get a great group with great DPS then I become useless in a different way.. they don't really need a tank. They run ahead anyway and aggro/kill stuff as if I wasn't even there.
Maybe I should stop going for capped resistance, shield usage reduction, +stats, etc and instead design a minimum Tanky tank that can do great DPS? I have heard of mSoc tanks that don't even run heavy armor, or do anything at all special to tank except run massive shields and use sword and board for big hits. Maybe I should go that route? My mSorc tank right now is still pretty traditional running heavy armor.
I like running dungeons, and I like the group finder. Every time you join the queue there is an adventure.