That sounds like an awfully large space to fill for any bookshelf speaker. I'm also in a large space and ended up with the M60s after originally ordering the M22s.

The good news is that Axiom has a great 30-day return policy. Try them out and if they don't work you can send them back. The M22 is a fine speaker, but if you can make the M60 work it should be a better match for the space you need to fill.