Been having the same dilemma as OP as well. My question, between the 2 classes, which pulls higher numbers in there respective dps role?

Just wondering how other guild are dealing with the only needing one tank for 8 man OP's. Have heard that once you progress into hard and nightmare modes you need 2 tanks, or will this still gimp you overall on certain fights? Curious if 1 of our tanks should all out switch to dps or not at this point.

All of the people crying about Assassin tanks are either very bad players, or have simply not gone deep enough into the OP's to truly understand yet. Yes vs multiple mobs we can and will take more damage due to dark ward losing its charges much faster. However, against bosses we are currently the best tank spec atm (from personal prospective anyway). Our threat is amazing, our mitigation (when stacking the correct stats properly) is rediculous, and our EH (effective health) is slightly greater than the other 2 tanks. We are however, much more gear dependant than the other 2 tanks. If you are willing to put in the effort of gearing properly, and doing some research on which stats you want at which %'s, Assassin tanks are an absolute asset to any group.