Blizzard's current Event system contains bloated events that aren't really easily readable or, to some degree, even reliable. Currently the only method that damage, mana gains, heals, etc are passed to the WoW client are through pre-formatted and pre-localized strings. Blizzard could make everyone's life easier by changing those events into simple numbers and name arguments passed through the event handlers and have their chat frames parse those on the client side. That would severely reduce the amount of memory hosed by DM addons. But they don't. So Ace2 or not, its most likely not going to make much of a difference in how much memory is pwned by the AddOn.