All good advice, but I might consider that possibly, if you don't have a very technical soundman, maybe the digital boards are a bit overkill and confusing..?
Something simple, with one knob per function might be able to be worked by a wider variety of available helpers?
Well the Bose L1 ( or 2 for stereo ) may well be the easiest sytem to get up and sounding good in a room without a lot of technical knowledge. Plus its sound quality would be best suited to a church. It's not like you need a system with a lot of punch in that situation, but simply one that fills the room well without being overbearing. And is much less susceptible to feedback problems than a conventional system which makes it ideal for both speech and music.