[jseth]

I realize that this is not the answer you may want to hear, but, given your situation, I would strongly recommend that you check out a good soundhole magnetic pickup, It's not going to sound all that acoustic-y, but it will give you a much more manageable signal in that rock group format.

Any of those soundboard pickups you mention (K&K, Trance, etc.) are going to be problematic at higher volume levels... the Anthem "might' do okay, but you'd probably be running it nearly fully on the UST portion to avoid excessive feedback - and the Element IS the UST portion of the Anthem pickups.

The most cost effective solution would be to stick with the Element in the J-45, and possibly get a preamp that has the tone shaping capability that you require.

The issue is that, when playing in a 5 or 6 piece group, you really don't want all the rich, full, resonance that a great acoustic tone has... you want something thinner that can "sit" in the mix of all the instruments and voices without adding a whole bunch of lower frequencies. It's a demanding proposition!