Yeah, I've been finding that the vocals sound fine up front but are getting washed out as volume creep sets in. I mostly blame our jackass lead guitar player
We used to do the totally ampless thing with electronic drums - that was a breeze to keep balanced - almost totally by watching the meters. Now we rarely put guitar amps and not much drums in the the PA for smaller/mid-sized gigs. That makes it a little more complex.
This Soundcraft mixer has two Digitech guitar direct to PA channels. I spent some time yesterday tweaking it. The Blackface Twin channel is reasonably decent. It certainly serviceable as an emergency backup. I couldn't resist cranking up the 80s metal setting and seeing if the neighbors would complain
When we have some familiar faces in the crowd we will enlist them to give us some feedback on balance and such.