While the internet forums may not be the most accurate place for getting a positive view on about anything really, I based my comment on the general competence of church/worship audio engineers as presented by TB

.
Over here the church music isn't amplified so no real experience about the sound levels, professional approach or lack of it etc.
it's what you would think it is over here...anything from $500,000 permanent installations with huge choirs and bands, all-acoustic with piano and organ, and trios using cabs on poles.
but i'm of the opinion that people are smart until proven stupid, and i know that's been my downfall in life but what can i tell ya? so i'm going to launch into a general rant directed to nobody in particular except maybe fokof

: here goes:
the key to a good live mix lies not in how much isolation you can get, not in what mics you use and where you put them, not in how expensive your board is...it lies in how good the performance is, how good the communication between band members is, and how inspired by the performance the soundman is to make it sound as good as he/she possibly can with the tools they have.
having said that, there is certainly no reason not to optimize your setup as good as you possibly can. do whatever you can that's reasonable to get the sound happening and fix what's not working when you can. but don't make the performers uncomfortable. how happy can a drummer be to be stuck in a plexiglas box? how happy can a guitarist be if you make him turn his amp toward a wall and he can't hear it? and maybe some people in the band need to be together because they depend on each other to get through the gig. if you try to isolate things too much, everyone ends up isolated. and then they lose perspective and start trying to compensate for it by sucking.
making the performers comfortable should be first and foremost, always. if you're getting unwanted artifacts from a setup that's not the most sound acoustically, try to fix it the best you can. move mics instead of people whenever possible. and if there's something you can't overcome, try to make it work as good as you can. like i mentioned earlier, if there's bleed you can't do anything about, eq around it by taking the instruments that are bleeding into each other's mics and mix them as a whole. if the band is happy, they play better, and a band that's playing well and has a good balanced sound within themselves will always carry you through even if the mix isn't quite perfect. if the mix totally sucks because of it, that's a whole different story, but just be reasonable it and don't sweat the small stuff just because it's not by the book.