[7rojo7]

The big diference is in mono, S disappears, in xy it doesn't. You may want this.
Your M better be pretty good!
Originally M/S was used with an omni and a fig8, to me, this makes better recordings for music (if you have to use M/S) and like this you can control the lobes of the omni pickup besides synthesizing stereo.
For 'Stealth' recordings in noisy places, indeed this is where cardioid and fig8 M/S would be useful as you will need to be able to 'focus', however, you still lose the S in mono. xy can be encoded to M/S as can any stereo source, and when xy is encoded to M/S you will not lose the S. if someone is brave enough to trig it out go ahead, make my day.
I find M/S to sound like an effect, as I do Blumlein (I use blumlein for recording BKG VOX with a pair of reflective gobos at 60 deg 3 times the distance as the mic to source, I had the pleasure to record the Roches like this once, with a C24), xy may be boring but its detail is realistic (discrete), just put it in the right place.
For me M/S has worked only when it's very close to the subject, but it lacks realism, the further away it is the more mono it becomes (like any other array), with a cardioid, the proximity effect is going to make you go searching for an eq, you'll have to be far away so that you're M can pick up the whole subject, can't get too close or you lose your sides with the cardioid pickup and too far it starts to sound weak and honky and the sides also (as fig8 has a more pronounced proximity effect than cardioid) this gives you a very limited range of distance to where you can place this array, with an omni you have a larger leeway. All in all it's never been practical for me, audience mic, but ORTF works better there, SFX if you don't need to catch the Doppler effect faithfully.
I have an ATM825 and it is LR, not xy, good for OH, stereo Ac Gtr. The Schoeps looks like an LR also, the Rode is xy but not adjustable (for stealth this is good) but seem 'fragile' for stealth, great specs, I wonder how it's voiced. I would use 2 CCM4v configured like a standard side address stereo mic (C24, 424, SM2, U69, etc...), I'm sure you could figure some way to mount them sturdily. The mount for the side address M/S for the CMC bodies would work, maybe they have that for the CCM also. OMD. I have 6 CCM mics and I adore them. Line makes some interesting mics as does Josephson, I'm dying to be able to hear them.