The front of an MK 22 has a screen which is finger-proof unless you have very tiny, very jabby fingers made of a hard substance. What you see within the metal ring is not the diaphragm, which is safely tucked away inside the capsule. This type of capsule (or the MK 2 H, which has a similar ring arrangement) should be no more fragile in normal use than other types. However, I don't do stealth (with Schoeps mikes, anyway), so I'm not sure what special hazards may be involved there.
I record mostly classical music so YMMV, but these have been my favorite capsules since they were in beta test. Schoeps makes a variant of the STC stereo bar called the "STC 22" which gives an ORTF-like arrangement, and I typically use these with a pair of Colette cables and that stereo bar.
--best regards
Speaking from personal experience, I've been wanting to give Schoeps some feedback that I'm disappointed with the design of the mk22. Functionally, the screen/grill does its job of protecting the insides. However, that screen is very VERY easy to dent, and in fact one trip into my gear bag resulted in a dented screen. Now, it could be debated if a dent is the same as damage, but the fact is they were cosmetically degraded after a single trip to my gear bag and the dent ended up degrading the value of my capsules significantly on the used market. I don't really feel this was due to mistreatment...unless storing caspules on body is considered mistreatment. In this case, I left my 22s on the bodies one time after a show and the damage was done. To be clear, the dent resulted from incidental contact of something in my bag with the end of one my mk22 capsule...not due to me throwing the mics around into and out of my bag or abusing them. Personally, I'd consider this normal field use.
One the one hand, I was mad at myself for not being meticulous about restoring the capsules to their vials after use. After getting them new, I knew from looking that the screens were delicate, so after I saw that the capsule got dented, I was mad at myself for not doing what I knew needed to be done to protect them EVERY time...just forgot once. On the other, after giving it some thought, I was a bit peeved at Schoeps for putting out such a flimsy design that, due to what I consider 'normal' handling, my gear ended up devalued. I've come to expect more from them.
So, yes I agree with you DSatz that the screen is finger proof, but otherwise it's just not field worthy...at least not to the point where you're not taking a risk of damage if you do take them out and suject them to the rigors of location recording.
In my case, I ended up selling my pair for $900 less than two years after I bought them for I think $1650. I feel the poor design alone ended up costing me about $300 on the used market.
Ever since, I've recommended to anyone that asks, if they want gear that retains value, to avoid the MK22 until the design is changed to have better resitance to day-to-day bumps that result from field use.