For every person yelling at you there's like 20 who love you for it. I've had a person yell at me for dpsing in the same run he was complaining it was taking too long to clear... Some people just like to complain.

With random groups I usually feel it out in the first pull or two then usually go to town once I feel comfy with the tanks damage intake. Runs with my FC... The tank knows he's getting three lustrate a per minute and whatever else Selene picks up lol. (I'd never really let them die but I'm not telling my FC tanks that... Gotta train 'em otherwise they get lazy and stand in stuff lol.)