I have just left a situation like you mention. Every one that was in the church that thought they new how to run sound got a chance, so they could be part of the worship exp. All it was was a mess! A person who KNOWS what they are doing is worth their weight in gold, as far as I'm concerned. I have 15 years exp. running sound for touring bands and outdoor concerts, but because I was just a "musician" (worship leaders words) I could not possibly know what I was talking about! It really brought down the worship exp., and created a very tense playing experiance. As a drummer-guitar-bass player, and now keyboard, I think that we, as musicians, have a better understanding of how things should be mixed, tones should be set, etc. For the last 2 years I played bars we hired a sound man. It cut into the pay, but the overall pressure was reduced 90% on the band because WE did not have to worry about where the feedback was comming from, is the vocal to loud, etc., we could just give 100% to the music.
And as for the Glenn Miller Orchestra, I have seen them a couple dozen times over the years and that has to be the hottest big band around! The musician ship is top notch, and to trust that to a "knob twister" is a total crock. I undrstand the need to cut costs somewhere, but when you do it to such an important part of the overall production just foolish. After working with some of the best sound techs in my area I have to say that if you find a good one, keep him (or her), make them a part of the band. The guy we had was an intergrated part of our overall show. He knew when we we're off, and could help us get a grip on it. Like wise we knew when HE was off, and could help out. The sound man can make or break your show, so don't skimp, get a good one!