As a Warrior tank, I haven't had any problems, or noticed anyone any closer on threat then pre 2.3. Threat seems the same. My PLD co-tank has mentioned that he feels something has changed with AoE threat for him. I'm not sure. He hasn't had any issue in T6, and has spoken mostly on Expert dungeons.
There does seem to be something that has changed with mob pickups though. For instance the T6 slugs definitely run toward boss/MT first, even when they haven't been touched by MT. This has happened in both our FC raid groups.
In T7 I definitely noticed odd behavior with Lamia pickups. I'd hit with a Skull Sunder within .5 seconds of its spawn, and it'd run out to mid and back. This isn't the usual, move because of slow pickup, or healer built aggroe, it was on me and had me targeted 100% of the time. It would happen with Tomahawk pickups from far one as well. Nothing unmanageable, but just messed up starting threat/IB mitigation a little. I noticed this problem in another one of our FC raid groups, so it wasn't just me there.
T8 nothing weird with Dreadnaught pickup. Ran straight for tank in both groups.
T9 I don't really recall any strange behavior on Golems. They seemed to stick and not run around much in both weeks since patch.
Syrcus Tower, no issue on any threat gen or add pickups. I usually tank everything at once, and never lose threat unless an impatient DPS/heal pulls the trigger before the group gathers.
Expert dungeons, I have no issues. I just noticed things are spread a little different, with more mixed range and hitboxes. Also they generally form different triangle spread out formations that cause AoE threat moves to miss if the group isn't brought together right. So in my opinion, there could be a phantom ShO/Defiance error that snuck in (happened before, so possible) but I personally am not noticing or seeing it.