Besides OoTS: Vanilla Stone Wardens, Item Vault, Proper Time Hounds, the Crucible, Marson's Bosses Gone AWOL, New Gem Types, Tomes of Knowledge, Gnomes, Bazaar, AEther Operators, Campaign Uncapper, Improved Auto-explore and Rest, Chaotic Races, The lost city of Vulcus 1.4, and Adventurous Arcane Combat. Kinda' need to get around to checking how some of those interact with OoTS, actually. Can see there being some oddities with the gem types and tomes in particular...
It's... not unlikely there's some kind of conflict, really. Like said, just need to get around to checking without, which'll probably not be tonight (if I start messing around with T4 now I'll probably not get to sleep at a decent hour

). But hopefully within 24 hours, heh.
There actually
is a minor conflict with AEther Operators, if you were curious. It also has a talent called Firewall, heh. Not even remotely major, and easy as pie to fix (I just renamed the AO one, ha). Though if anyone was wondering, I've got that particular addon because Chaotic Races without a way to delete talents... doesn't end well. And that's about the least impactful addon with the functionality that I've noticed.
... incidentally, if you even remotely cared, psi-held weapons don't show for... any of the new ragdolls, far as I can recall. Basically a complete non-issue, but if you ever consider doing anything with opening up the avatar talents and/or monstrosity races to more stuff it might be worth knowing ahead of time.