Having the M5OWs as the rear surrounds is a sound improvement over the QS10s in my room. I went through several movies last night and having the monopole speakers firing right at the listening position was a major boost in directional sound. In all fairness the QS10s don't have the optimal set up in my room because the walls aren't up and there is nothing for the sound to reflect off of. I should have an opportunity to hook them up as rears this weekend.
I think it really comes down to room acoustics. I've been swapping out the QS10s, M5ow's, and M80ow's, plus several other units from other manufactures including SVS's Ultra surrounds, and a few others. I really like the QS10's as it works best in my environment but i'm finding myself going back to the M80ows. They don't go as low as the 10's but they have incredible imagining, better than anything else i've heard so far. it's just hard to give up that low bass the QS10's have. I've not heard the m5 bookshelves, but with the cabinet volume those are probably the best choice around.
