The D112 is an AKG mic, affectionately known as the "egg". AKG have recently released an update of the original D12 - haven't used one yet but the original was far superior on kick than the egg in my opinion (I own a D112, and I often find myself rolling off at about 1.6 - 2kHz when I use it). My favourite "kick" mic is the EV RE20, which is not a kick mic at all - it was designed as a radio announcers mic. One mic that we used to see in kick drums a lot was the Beyer M88, designed as a stage vocal mic - I never liked this mic for either application and always replaced it with one of my own on walk ins. Thankfully, you hardly ever see them anymore. I'm not trying to start a fight here, and I know many engineers that still like the M88 - each to his or her own.
To return to the original post, the MD 421 used to be used a lot on toms in the 70's and 80's, but they are out of fashion in this application these days in favour of less unwieldy mics - the 421 is HUGE! I still like them on toms though, and as Richard Monroe said above, they are a great sax mic. Also mentioned above (by Steenamaroo), great on guitar cabs especially when used in tandem with a 57 - you often see this mic combination in gtr amp modelling software like
NI Guitar Rig. I wouldn't worry about the low end roll-off: a friend of mine thought his 421 was damaged until I switched the roll-off out for him. 421's aren't the worst kick mic in the world, but that roll-off has got to be out. All up , the 421 is a great dynamic mic for detail in mid-range frequencies.
It strikes me that I haven't said anything here that hasn't already been mentioned, so I will: Fellow Aussies who are old enough will remember the day when Prime Minister Gough Whitlam was dismissed from office, standing on the steps of Parliament speaking into the original version of the 421 (this one was beige, not black): "Well may we say God save the queen, for nothing will save the Governor General"...
Cheers,
brento