Not really. I never use quelling strikes and never steal aggro in level appropriate dungeons. It's all about timing auto attacks between abilities. When helping with lower dungeons, though, it seems because my gear level is so significantly higher than the tank, my aggro builds up faster, but if I auto attack for a few seconds, it usually counteracts that. Just assume if someone is higher geared than you, you'll probably have to work to keep that aggro (assuming they don't know how to control it.) You can usually get a feel right away.