I posted this elsewhere, but there's much more discussion in this thread:
I was in a VoD raid on the day U7 was released and Suulo behaved very differerently than I've seen before.
Intimidate was almost completely useless in holding his aggro. Our party had a fighter with Intimidate in the high 60s, and just about any time another party member whacked Suulo with a weapon he'd spin around and attack, ignoring our Intimidator. Most of the time he'd do this while the Intimidate symbol was glowing above his head. The amount of time spent in an Intimidated state didn't seem to matter - we'd wait 7 or 8 seconds sometimes and let the tank hit him a few times to solidly take the aggro, and he'd still spin around when attacked by the rest of the party. Sometimes he didn't even wait to be attacked, he'd turn on us as we were moving up behind him. I've been in VoD raids previously with Fullpozzy or others intimitanking, and they were able to lock him in place perfectly.
His behaviour seemed subtly different in a few other ways too. He was generally more spazzy and prone to jumping away, flying around and/or aggroing on people on the other side of the room. Sometimes, he'd jump away from the wall, loom over one party member and stand there looking menacing for 6 or 7 seconds, but not attack - kind of like he was trying to use Intimidate himself.
It was clearly not due to lag, mistiming of Intimidate, other system issues or gameplay mistakes.