You do realize that reverb units are generally samples or digital approximations of the sounds of real spaces, right? If this church is a former JC Penny, then sure, but if it's an actual old school church then the room sound will likely be better than what any digital unit can provide. Yes, you have to move the mics around rather than change digital parameters, and I get that may be more trouble than it's worth, but I'd at least give it a try.
Yes, I realize this. My reasons are thus:
1. Most of my favorite room/crowd mics cost $350-2000 each, which seems to beyond the budget.
2. I often process said room mics with multiband compression and do some sidechaining, processing which is not available here.
3. Not all churches have great acoustics (which you noted).
4. Depending on loudspeaker quality and deployment, the excitation source is not inherently pleasant. This may add, or it may not. As you noted this also dependant upon the position.
