There isn't many people that do that. I've only had it happen twice when people berated me for not pulling enough. Simply ask them if they'd like to tank, it tends to shut them up. :3 As for taking too much, that's really only an issue if you can manage your CD and if you trust your healer. xP If you fail, and they get mad, just say you're testing your ability with the current healer, and you out stepped your bounds. Don't resort to blaming anyone, though.
