Grif, welcome. If you've been pining for the M80s the past five years, then yes, in that sense you made a "mistake" going with the M60s. In reality, however, in your setup the difference between them, especially with your 25-31, may be insignificant. Alan has indicated that the difference above the lowest bass is very small and you may be disappointed if you've been anticipating a "big" difference. Keep in mind that the M80s are slightly more sensitive and require a bit less power, so that at the same settings it'll be a little louder and sound better simply because of that if volume levels aren't precisely equalized.
From what you report, you actually appear to have more dissatisfaction with the VP150. A suggestion for a change would be to consider using a different center, such as a vertical M22, if you can fit it in to your setup.
