"MoP" in this context means Patch 5.0.4, so unless you're in a region that hasn't updated yet, you can use Ion right now, and Macaroon shouldn't be working.
Unfortunately, I'm stuck using Bartender for now, as Ion isn't really usable for me in its current state, with no support for custom state definitions, dual spec swapping, or even different bar layouts/keybindings for different characters. The loss of Macaroon_Bound is pretty painful, too. I couldn't find an up-to-date direct-binding addon for spells/macros, so I've had to resort to filling up a Lua file with class checks and tons of SetOverrideBinding lines.
Ion's completion is probably the most-anticipated addon event of my life.
