Mid-side decoding wackiness

[Magnetic Services]

Recent thread got me thinking about Mid-Side techniques and how the decoding reacts to mid and side mics which are picking up different information (or processed before decoding). If the stereo effect is achieved by the side mic adding/cancelling with the phase of the mid mic, then ideally you'd get the "perfect" sound with 2 matched microphones (one in figure-8 mode and one in cardi). But what happens when you use two wildly different mics? How much does it influence the decoded result? Some scenarios for example:

-Dark mid mic, bright side mic (or vice versa)
-Dynamic mid, condenser/ribbon side
-Condenser mid, ribbon side
-Compressed mid or side mic
-High- or low-passing either mic
-Other effects on either mic before decoding (phaser, expander, time nudge delay, etc.)

In any of these scenarios, would some of the frequency range stay centered and fail to decode into stereo? Any weird effects possible like comb-filtered sides and normal mid or transients staying centered?

...Or am I just overthinking it and all that happens is you get an interesting drum sound?

[vvv]

I've done drums many times with a condensor for the mid and a ribbon for the 8- works well on stereo playback, and different mics give different results. I'm not much of one to mix for mono - my operative theory being that most mono listening is done because of compromised or inferior playback devices, not by choice (leaving out us, as the recordist/mixers). I've never noticed any problems re the decode.

I do the below frequently, taking it a step weirder:

I do this most often as an effect on guitars and percussion. I'll pan everything I want in mono, and set up a dynamic mid and a ribbon 8; you needn't even have the mic's equidistant from the playback source - I usually use an Auratone because I want the limited frequency range. Often, I'll skip the mid and just record the 8, then process the original mono track (typically a guitar) as tho' it's the mid.

To the extent I've tried it on drums, it's only been on the kit submix, and so it gives a big stereo picture, but not necessarily one where anything is more right than left.

Is it actually resulting in M/S? No, but it is giving a ambient stereo effect that you adjust as if it were M/S. And of course, if you place the 8 further from the sound source, you get that much more room ...

Does it break down to well to stereo? Who cares - but it's not horrible.