It just seems like the QS8's are a better speaker then the M22/M2/M3 bookshelf speakers, so I was wondering if you could use the QS's for your mains?

I'm not sure what makes you think the Qs8's are better speakers than the others you mentioned?

The Q's are a different type of speaker and designed specifically to address the surround channels. The quadpolar design with 4 drivers firing in-phase up/down/left/right are intended to "wrap" or "envelope" you in the sound effects.

One basis of their design was to simulate the same outcome of theaters that place many direct radiating "bookshelf" type speakers along the sides and rear walls of the movie theater. Axiom engineered the Q's this way to satisfy the movie engineer's requirements for the "surround" experience, all in "one" speaker.

For the left/right mains you want the sound directed towards the listeners ears, not spread out. Your soundstage would totally be ruined with bi, di, or quad "polar" type speakers.

In regards to your statement about them being better, this would only be true if your referring to their actual purpose of surround speakers.