You should get Qs8's for the "side" surrounds, no bookshelf or floorstanding speaker can give you the same experience. They were designed to give you the same experience as the recording engineers intended in theaters.

As far as the rears, if you don't have room, maybe sell the m40's, or keep them for another room, and get something smaller for the rear channel. jm2cents

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