Hrm...Seems a bit specific...Are you saying that these could only be slotted into specific Epic Pools? And if so, that means that that some of these "EIOs" would be pretty much exclusive to certain Archetypes. And what about PPPs?
Open Archetype Suggestion thread!, Kirsten's Epic Weapon Pools, Feudal Japan, Etc., Alignment specific Rularuu iTrials!
If Masterminds didn't suck, they'd be the most powerful AT in the game.
I misread the thread title and thought my Old MacDonald character was finally getting EIEIOs.
I personally think a MUCH better idea would be to revisit Hami-O's.
Hami's should drop during the Underground Trial. At a minimum they should be included on the loot table.
Hami's should drop during the Seed of Hamidon zone event.
There should be entirely NEW Hamidon IO's added, perhaps called Praetorian Hamidon Enhancements.
Some ideas:
An Acc/Dam/End/Rech Hami-O
A Buff/Recharge Hami-O
An Acc/End/Rech Hami-O
A Move/Rech/Resist Hami-O
Etc, etc. I think this would be verrrry nice indeed. 
Plus the Freem'rs would get a boost!
So, I love the idea of ATIOs and have come up with a few ideas for them or more the procs :P They are more fun to come up with. Maybe link each ATIO in with the lore.
Also, how about epic IOs that only go in the epic IO slot and provide bonuses to them. Here are some ideas.
1) Command of Lord Recluse - Adds a proc to summon a pet on the attack it is slotted to. The pet basically works like a DoT, but is just thematic.
2) Statesman's Resolve - Proc that goes in a resistance slot that every 120 seconds, will go off once, granting a 5 second immunity to mez effects.
3) Back Alley Battles - Defence debuff proc on an attack for brutes
Epic IOs:
Cold Hearted - Goes in any defensive cold power and adds a resistance to cold and fire damage increase
Weapons Expert - Adds a recharge bonus proc to any weapons power
So what do you think? Just a rough idea.