I have had good results with a pair of 4050's in a Blumlien (sp?) configuration. Or a pair of KM-184's are not bad in an X-Y setup. It depends on the sound of the room. Use a clean mic preamp and listen to the placement. It has worked for me.
I fly (mount on a 12" wooden base) 2 - 4 Crown PZM's (depending on room size) into a very clean pre and get out of the way. These are the real PZMs not the sound grabbers. To me its the most natural sounding way to capture a choir the way I hear them from the podium.
Placement from my experience becomes critical only because of phase problems. Keep 'em far enough away where you're still getting clean diction (at least 10 -15') and spread far enough apart to eliminate phase problems. The thing to listen for is blend. You certainly get lots of dynamic contrast if you're too close, but you'll hear individual voices that way. You can easily get by with 2 mics if the room is right.
Sometimes with room acoustic issues I'll put an AKG414 near the men for a little extra fullness.
Actually, I've found that this set up works great for many classical ensembles as well. Chamber orchestras, etc...Places you might consider using a stereo mic for a quick set up. What I like about it is that it tends to give a better representation of the ensemble's acoustic balance, eliminates the proximity problems of close micing, and captures the room at the same time. BTW - I'm not any kind of recording engineer, I'm using my ears to guide me as a pro choral director/ recording hobbyist.
Ditto above post. I've done choir a few times and the mics I expected not to need turned out to be the keeper tracks. You can always reject tracks but can not go back and add.
Also some rooms are difficult to impossible to tame. I have one that I work that's given me fits with reflections to mics. I can not hear them in room but the mics do, go figure. So do not give up after one bad room or one bad experience.