I know there have been changes to the m80 crossover in the last 2 years for sure. When I thought I was having problems with my m80 The folks at axiom said I would have to send it in for repair (instead of getting a replacement m80 sent to me). They said that this was due to changes in the speaker (I assume the crossover) That they called their "continuous product improvement"... otherwise I'd have two slightly different sounding speakers.
I have an m80 v2 bought approximately 2 years ago, but I'm guessing the ones they are selling now have been changed a little.
I have no plans to get the "latest and greatest" V2, because within a few months it may be outdated again... You never know.