As a melee DPS, I don't think it hurts to ask. "Hey, are you guys okay if I do a big pull to see how this group handles it?"

During the entire 2.+ line I've had one tank stop after the first pull and go "Oh shit, I have a MNK & DRG. Time to adjust my pulls." Sure, the healer, MNK & I were able to handle that big pull, it just took awhile.