Yo Jacob! The main reason they are asking whether this is for live sound reinforcement or for recording is because the sensitivity and detail that is so desirable for recording is a feedback pit for live sound. You say you like the idea of 2 LDC's, and then say ? SM81 and ?SM57, neither of which is an LDC. First, if it were me, I would *open that lid*! Then I would use 3 mics. Two identical small or large diaphragm condensers (either one will work) as a spaced overhead stereo pair, and a dedicated low frequency mic under the bass third of the soundboard, underneath the piano. Get a good stereo mix with the overheads, and then mix in a little of the bass mic until the feeling is right. For the overheads- SM57? No. SM81? That would be just fine. Or- AKG C451, C535, or C2000B, Rode NT5, Studio Projects C4. For more money, better options would be Josephson C42,
Neumann TLM102 (no, not TLM103, although they would work fine also, for more money), Neumann KM184. To die for- Schoeps CM6- unfortunately, if your church can afford those, get out now, it's a cult.
For the low frequency mic, I would use AKG D112, a dedicated low frequency dynamic. I have mic'd grands and baby grands that way, using C2000B or KM184, and the D112, and gotten results that were appreciated by professional concert pianists. Of course, doing live studio recording (with everybody playing together) you *will* get mic bleed. That is, the overheads will pick up a fair amount of the rest of the group. Embrace the bleed. It is unavoidable in that scenario. I would, however, place the overheads pretty close to the piano, not more than 24", so you can turn them down a bit and reduce the bleed. The D112 is a close mic, like 4" from the bottom of the piano. Good luck.-Richie