This is pretty well what mhorgel suggested only you'd have M80's as left & right fronts.
I think in a larger room this would certainly be a truly awesome system, no doubt - particularily excellent for DVDA/SACD...
I'd also go for QS8's for HT surrounds if cost wasn't too much of a factor.
For the VP150 I'd ask about Axiom's upgrade policy and put it towards new purchases or likely better sell it on the internet EBAY ect. Nice thing about Axiom's is they seem to be easy to sell used.
One thing to remeber is the law of diminishng returns and I don't think you will experience as drastic a "wow" effect with towers all around as you probably did when you first got your Axiom system. But know doubt given an appropriate room and the resources to do this, I think it would be excellent!
Such a system is what I'm dreaming of some day. Nice thing is if you plan it right you can get there one piece at a time and have a great time along the way.