[Richard Crowley]

"muzician21" wrote ...
What about recording the singer and real piano well in the deader
acoustics of your house and adding a tasteful amount of good digital
reverb later?

The acoustics isn't particularly about the *recording* it is about
the *performance*. For the same reason that people (not just
opera singers) like to sing in the shower, but not in an overstuffed
closet. Classical vocal music is an *acoustic* "instrument" that
does not involve microphones in any way.

Would the acoustics of the church really yield better results?

For the singer, almost certainly yes. For the recording, probably,
but that can be controlled by mic placement, etc. etc.

Especially for an audition recording, the primary concern is getting
the best *performance* from the singer. If they are competent, the
audience is listening for performance primarily, and the recording
is only the media, not the message itself.