tbh the only way a tank is going to keep aoe aggro off me as a dps commando is if the trenchgutters die before the 6 seconds of the taunt are up. Otherwise, it won't happen.
[Edit: which isn't necessarily a bad thing, I can survive well enough and removing them from the tanks may help them survive as well, those things hurt a lot]
Not in NiM. I have to ask my dps to wait a few seconds before engaging. 2 withers and 1 discharge is enough most of the time, but as it only hits 5 ppl, there is a chance it does not hit a particular trenchcutter at all and he will run to dps on aoe, and in NiM that means dps is as good as dead unless he can be taunted off, which is hard as tab target feks it up all the time