I've only had sporadic opportunities to listen to them, but I can say with certainty that the M3s share the same tweeter unit as the M60s.
I would not describe the M3s as "laid-back". At the very high end they sound the same. The single 6.5 inch driver does not cover the whole frequency range as well as the M60's multiple drivers do (duh!). I'm not sure I could live with bookshelves sans sub, but I plan on bringing home some other bookshelf speakers just to make sure (sub in the upstairs gameroom would be out of the question).
Wife gave me the go ahead to start demoing all kinds of speakers from the local stores so long as I keep only one pair. And it turns out I have room for towers if I like - I'm thinking those Silver8s would be pretty damn good gameroom speakers!!!
