I am not sure if I had the exact problem as yours. But as discussed on the wowace forums from time to time, this kind of problem persists because authors of different addons use different versions of libraries.

Whenever you have a similar problem, you could either wait for the author to update his libraries, or you could check the versions of your embedded libraries. And then replace the older version with the newer version to ensure that they are not loaded simultaneously. (The design of Ace is that identical libraries are not loaded twice thus saving memory space)

So all in all, you could keep using Pitbull which is highly configurable.