If neither of those ideas work, and you do opt for the M60's, your room is certainly big enough. I'd do my best to get your ears at LEAST 10' back though. If you can squeeze another foot or two, all the better.
The powers that be at Axiom would likely let you purchase a pair of M60ti's and give you a week or so to A/B them with your current M22ti's. That would answer all your questions. Just send back the pair you decide not to keep. If my two little tweak ideas above didn't work, that's certainly what I'd do.
