I was thinking about adding two pair of M30s as rears and front heights but the wife's not to keen on the way they're gonna look. When I showed her the RCi in-wall speakers she said that they looked great and she could really go for them. Plus, they're paintable. They would integrate nicely when we re-do our living room since we're installing new sheetrock and alll the wires would be hidden in the walls.
However, I'm concerned about the sound quality. I'm looking at the RC85i's for the rears and RC55i's for front heights as I've read they're timbre-matched to the Monitor line (I have M60 fronts). How would they compare to using the M30s? I know I'd probably lose some cabinet resonance but I have no experience with in-walls. Any feedback would be appreciated.