I once overlaid the Soundstagemagazine FR graphs for M2, M3, M22 and M40 into a single chart. The results were very interesting.
M2 is much closer to M22 than M3 is, down to 100 Hz. Below 100 Hz, the M2 drops off sharply while the M22 and M3 both have relatively more output, but the shape of their curves below 100 Hz is very different.
I think the issue is that the M22 and M3 sound relatively closer than the M2 because they both have "decent amounts of bass", if you were to repeat the same test with the speakers set to "small" and a subwoofer crossed at 100 Hz I think you would find that the M2 was now closer to M22 than the M3 was.
If you cross over at the more common 80 Hz it's kinda hard to say which would sound closer
Having said all that, Hutzal's original point was that the M3 was more generally useful in the future, and that is absolutely correct. The timbre difference between M2 and M3 above 80 Hz is going to be fairly small, particularly if sidewall reflections are reasonably well controlled (since the biggest difference AFAIK is the off-axis response dip of the 6.5" driver around the "few KHz" range.
M2s, M22s and M3s are probably equally likely to cause colour distortion when placed near a CRT. I don't know if the 6.5" M3 woofer has a bigger magnet than the 5.5" M2/22 woofer, guess we could ask Axiom that.
