I have to tread lightly here because of my relationship with the Schoeps company--I don't want to be a shill. Thing is, I own a pair of Neumann KM 150 microphones and think very highly of them. Their polar pattern is extremely consistent across the frequency range, and the slight elevation in their high frequency response can give a nice bit of "sparkle" if the original sound is lacking in that dimension.
I agree that they're best for use in "boomy" sounding rooms, though, and since I have alternatives with much flatter low-frequency response, I wouldn't normally choose them for most full-range music recording. It seems to me that the AK 50 capsule was probably developed with film and video sound in mind, and for use as a spot (close-up) microphone, rather than for more distant general recording, given the slope of its low-frequency response.
Should I post the catalog curves here and compare them to speech microphones and standard studio microphones to show what I mean? The KM 150 is down ca. 9-10 dB at 50 Hz; a classic speech cardioid such as the KM 85 is -12 dB at 50 Hz, while a classic standard cardioid such as the KM 84 is ca. -2 dB at 50 Hz (all at the usual 1-meter equivalent measuring distance). So the KM 150 is about 3/4 of the way toward being a speech microphone, objectively speaking.
However, it can take EQ very well because its polar (directional) pattern is extremely consistent, even down to the lowest frequencies. People truly shouldn't be afraid of trying that. If you dial in the right curve, the result can sound every bit as good as if the capsule had had full low-frequency response to begin with. (Please don't argue with me about this unless you've actually tried it yourself.)
I also want to express my deep agreement with the fellow who loves the wide cardioids--I haven't tried Neumann's capsules yet (I'll bet they're really good), but I just mean that when the acoustical conditions are ripe for using that pattern for stereo recording, the results can be so delicious I could cry. They're the most fun ever. It's just that you really do need to get in closer, and the room acoustics and the layout of the sound sources all have to be working in your favor, or at least not completely against you, for the magic to work.
--best regards