Wow, thanks for that tech explanation. I have used MS mics as the basis of all my serious recordings since 1984 but I remain slightly hazy about the underlying theory! My go-to pair for classical recording was a Sennheiser MKH 30 and 40 (if I recall the models correctly), and that rear image reversal phenomenon was never very apparent, but of course when recording classical musicians in front, and the room reverb behind, there wasn't much to reveal any such problem. Now, with the Zoom mic that weighs a few grams and is thus easy to hand hold and speak into at odd angles, the issue is more manifest (and as you explain, the capsules used would be relevant).
It grieves me that these days I have almost no chance of recording anything, let alone a classical performance in a good acoustic, but I am hopeful that before the end of the year I will be able to get some opportunities to discover whether the M3 is a breakthrough or a disaster! Probably somewhere in between.