You will never pull aggro off a competent tank geared nearly as well as you are. If you're pulling aggro, it's because the tank is undergeared.

Your rotation is going to open with 7.5 seconds of non-direct damage or burst, giving the tank more than enough time to use his enmity building single target rotation just fine. You are no Black Mage popping fire starter procs at the beginning of a fight on top of 1.5k fire I crits. Your damage takes ramp up and if the tank is losing aggro, HE is at fault.

Multi-target is a different matter as most tanks aren't used to tab targeting threat build up. But any tank with a summoner in group will learn to keep cycling targets to keep aggro when you bane DoT's.