Drum overheads not a problem at all.
We have four MV-691s at our studio, along with a Telefunken SM-2 (stereo KM-56), and all have been used as overheads and/or front of kit with no issues whatsoever.
While they might not be my very first choice on a hat, I think as long as you take care to avoid the air blast of the closing hats you'll probably be OK. If it were me, I'd try it without much hesitation.
I cannot personally speak to "under snare" (and of course even that might depend somewhat on whether you're recording Meshuggah or the Jeff Hamilton Trio), but I have definitely heard of KM-56 being used under snare by others (notably on many Beatles sessions, according to the Recording the Beatles book). However, prior use doesn't necessarily indicate "safe for the mic."