Steve,
Every now and then I also get an upgrade itch as well. I have the same speakers across the front as you do as well. I have always felt from the beginning that the vp150 was lacking compared to the rest of the line, so if you want to upgrade something I'm betting that the vp150 to the vp180 would be quite noticeable. The towers may not be as noticeable unless you have a large room.
For, me I'm waiting until the point when I have a larger room. My room is only 12' by 16' with an 8' ceiling. So if (when) I move into a larger house and hopefully have a larger theater room then I can upgrade the m22's to m80's and the m22's will become width speakers. I'd also want to upgrade the vp150 to a vp180 at that point. I can't do it now since my TV and equipment stand isn't large enough to support that large speaker. But, if it were I would definitely do it soon.
