It's significantly worse aggro. Let me put it this way. I had a PLD spamming RoH one day in HM Ifrit. I got fed up with it, because it was stupid and was killing our DPS. After a wipe, I gave him about a 30 second head start, then I blew all my CDs and unloaded on Ifrit. The only reason he kept aggro is because I actually switched targets to nails.

We all know that if I give a real tank using proper threat generation a 30 second lead, I'm not ever going to pull aggro unless something goes horribly wrong.