Unholy Tank here.
A few things on talents that i have played arround with.
CE is useless right now. Does pitiful damage and is very unreliable for threat in 10 mans or Herorics. Although it was greatly amusing when I did use in 25 mans to blow up the dead melee :P
BCB: This is an awesome threat talent when you are past the point of worrying about getting killed. Sitting in almost full Naxx 25 gear im not really worried about dying, im more worried about threat and moving through the instance faster. Also, I am ussually DPS on the one tank fights, so this is also a nice DPS boost there.
Gargoyle: Get him, use him, love him. That is all.
Necrosis: I like this talent as right now, most of my damage done is from RS and Necrosis scales nicely with RS damage. This may change after the patch, but only time will tell.
Outbreak: Its very lack luster and i will prolly be dropping it soon. BB does very little damage as it is, and im only using pestilance to spread the diseases.
AMZ/AMS: I personally like these 2 talents and use them in my 25 man build on a regular basis. There not game changing, but 5% less damage taken from spells and another CD for spell damage are nice.
I am still out on Wandering plague for tanking. My problem is that I am trying to balance threat vs. mitigation vs. being a DPS/OT. If I was just MTing everything and never DPSed, then wandering plague is crap. My crit in tank gear is like 5. Impurity would be better most likely, although I have seen math on that not being so hot either.
As far as the ghoul, it looks like it might be worth having even as a tank. 500 to 800 extra DPS in a 25 man is very nice. plus, then I wouldn't feel so bad about taking Ravenous dead.
Hopefully duel specs comes soon so i dont have to balance specs and glypths. /sigh
I cast the spells that make the people fall over.