I was debating on twin 350's versus an EP500 to accompany my EP600 downstairs. I ended up with the two 350's and my 600. It is tricky to get everything calibrated correctly, but once done you can get very even bass around the room.

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