You're not forced to using maximizer, you can use the build in "windowed mode" that wow offers, but when cramming 5 wow's onto 1 monitor you really can't afford to waste space on window frames and title lines IMO.

An added benefit of maximizer is that it organizes your wow windows they way you prefer every time - if you do warcrafts "windowed mode" you will get all 5 wow windows stacked on top of each other every time you start and have to manually drag them around before you're ready to play..