Long story short, after completely reworking the mix I was able to make everything sound great! You could hear everything crisp and clear! I ended up running the sound between 90 and 95 db without a single complaint! I got a few dirty looks from the other sound guys, but really I was expecting that.
I'm glad to hear you're making progress. I think you may have actually touched on the problem in your first post, when you said that the stage volume was too loud, and it sounded very hollow. It's been my experience (not in church, but out in the rest of the world) that when somebody says, "It's too LOUD", what they really mean is they don't like it, or that it doesn't sound very good. I've actually been in that situation before, with a lot of monitor wash and the PA fairly quiet, and plenty of people in the audience were telling me it was too loud. When I bit the bullet and pushed the master fader up to where it had been for sound check, it sounded much better to me, and louder of course, but the complaints stopped. And it wasn't because the complainers left!
I'm not sure why older audience members do more complaining about this than the younger ones. Maybe it's because of the hearing impairment that Art mentioned, or maybe they're not as willing to put up with mediocre sound as younger kids are these days. You might make the argument that the older generation actually knows what acoustic instruments and voices should sound like, as opposed to kids whose only frame of reference is dynamic range squashed MP3s in cheap ear buds.
Anyway, good luck with it. If I had any advice it would be to get the best sound you can with the musicians and tools you have now, before throwing more technology at the problem. Only spend money on the gear if you can clearly identify something that is coming up short. DON'T be one of those church sound guys who is happy to spend somebody else's money to satisfy a gear lust habit.
GTD