I'm currently trying out Oblivion companion mods right now, with some interesting results. Some of those gals don't get on with each other at all, though it looks like it's down to the game's AI rather than mod incompatibility.
Gabby and Valeria got on fine, but then I got Viconia DeVir (who is quite the hottie), and that kind of put the cat among the pigeons. I had to let Gabby go as she kept stopping to chat with Viconia and holding up the posse.
Then problems emerged with Valeria. She's configured as a sorceress, and when we're attacked out in the sticks she normally conjures up a flame atronach. Viconia doesn't like the atronach and attacks it. Valeria naturally then attacks Viconia and the two of them end up flinging whammy at each other while I'm trying to deal with the real problem. Right now we're in Shivering Isles (Mania), and I might have to send one of them home if they don't start to play nicely..