I always figured that the idea behind defender tanking was that it doesn't matter who has the aggro because you've debuffed the enemies or buffed your allies so much.
EDIT: Procs should get you aggro at the same rate that any other type of damage would. If you're the first to attack and you do solid damage, you should be able to keep aggro from most of the enemies until they're dead.
The answer is not really. Damage always helps you get aggro, but a proc in time's juncture will only fire on a particular enemy every 50 seconds (a 20% chance to fire every 10 seconds). In practice it will feel better because against a large group some enemies are likely to get hit every 10 seconds, but that damage on its own is unlikely to overcome the aggro of other players unless you are on a team with very low damage output, or few AoEs. So I suspect you will notice almost no change in your ability to keep aggro.
Draggynn on Virtue: lvl 50 Storm/Psi, 1389 badges
Draggynn's Guide to Storm Summoning(Gale-Tornado, updated 6/25/2011)
Avatar by Wassy full reference here
I have a Time/Sonic defender who pretty much never dies (softcapped positional and psi defense, and 69% smashing/lethal resist). I have been musing on finding ways to help him hold more aggro, seeing if I might be able to make him into a sort of MacGyvered tank, but he's already got four pools which means Presence is probably a no-go... however, how good are damage procs at drawing aggro? If I put the damage proc from Impeded Swiftness into Time's Juncture, would that help a little at keeping things mad at me?
If I drop Hasten I could take Provoke... but then I would be dropping Hasten.
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