But then again, those are posted specifications...

Measurements by SoundStage! at the NRC give them 1 dB difference between their sensetivities.

M22ti
M2i

And for comparison, here is the M3Ti which is actually LOWER than the M2i.

In comparison, Axiom rates the M2i as 87, the M3ti as 88, and the M22ti as 89 (all anechoicly of course, unlike other manufacturers which ONLY say the in-room spl).