I recently upgraded my M80ti to M80v4 and my M22v3 to M22v4. First of all there are noticeable differences going from the "m80ti" to the m80v4 and also the same was noticed going from the M22v3 to the M22v4. I'm extremely happy I used Axiom's trade in program to upgrade my setups. Long story short the differences that I noticed right away is that the V4's are smoother sounding but do not lose any of that detail that Axiom is known for. I have my M80's set up in the family room that is 13x21x8 and then I have the M22's set up in my office which is 8x12x7. Both sound very similar. I would agree with Mojo that there are differences in the soundstage and presence. I'm giving them similar power and currently have the crossover set on both to 80hz. M80's can easily go down to 40hz and sound VERY good and have good bass output. I actually like having them at 60hz but I'm testing out 80hz for the time being. M22's in my opinion sound best at 80hz so depending on your sub, having the flexibility to go lower than 80hz might be important.