Korby
Tracey used to bring those into the studio I worked at quite frequently (he used to live in Pittsburgh). I actually though more highly of some of his old Neumanns and Royers, but maybe I just never heard one on the right instrument.
one of my old teachers had the Convertible microphone and all 4 caps. We used the C12 capsule for some male vocals through a Neve preamp and it sounded fantastic. Of course different microphones sound better with different voices. We tried all of the capsules and decided the C12 was best. All of them sounded great to me for vocals. A nice, rich, and full sound. we needed to give it just a little bump up in the high frequencies(~2dB around 13khz) and that was it. I've heard some samples on other instruments, but haven't recorded any.
Next week my modified Apex 460 tube microphone with the Peluso CK-12 capsule will finally be arriving and I can't wait to try it out. At $600 for a completely stripped and modified 9 polar pattern tube microphone, I figured it was probably the closest I'll get to a C12 without spending thousands.