Disclaimer: I haven't read the whole thread.
My little church plant church that meets once a week in a small park pavilion uses one of these systems, with the "sub" included. We frequently play music for background noise while we eat, and it gets used for acoustic guitars, singing mics, and speaking mics on a regular basis. I even played my baritone acoustic guitar through it.
My impression is that it still brings a very unnatural sound to vocals, much like their home audio systems do. Highs are simply lacking, especially for outdoor and large venue applications.
Bass is pretty much nonexistent. I'm not sure what frequency my baritone goes down to (its tuned to a low B much like a seven string guitar) but I was not impressed with that little thing.
I would MUCH MUCH rather be playing thru/listening to a portable Mackie system with conventional mains and a real subwoofer.
However, if I was making good $$ playing small coffee houses solo, I'd consider the Bose unit. Still, it has that signature Bose sound, which means "no highs, no lows, just Bose".