I had planned to report in on my initial use of the system, including the 3Ls that this group virtually DEMANDED that I get ( ) in a previous but now hidden thread ("To Sub or not to sub, that is the question"), but I don't think Line6tony (with whom I've been in contact) has had any luck finding it - so.. thought I'd start a new thread.
In short - it was flawless! The M20d worked as it should have, and it really is quite intuitive. The L3s was not an issue at all - it made the sound really full. I had FBS enabled and it did what it needed to do in the admittedly odd space - (an open-air courtyard, concrete/tile floor, brick wall on one side, brick/stucco/glass on the other, open in back, tile behind us). Played with a keyboard, drums, bass guitar, me on acoustic guitar, 5 singers... even hooked up a Mackie 15" Thump for a monitor... absolutely everything did what it was supposed to do.
I was even able to record the whole Easter Sunrise service and it worked without a hitch (Sandisk Extreme 32g class 10 SD card).
Happy camper! And thanks to all who encouraged me!