It is important for the front left/center/right to be matching drivers, you don't want to mix stuff up, if the best soundstage/sound is important to you. The surrounds are not as picky, however, it is nice to have an all matching system.

M80s VP180 4xM22ow 4xM3ic EP600 2xEP350
AnthemAVM60 Outlaw7700 EmoA500 Epson5040UB FluanceRT85