That's an interesting product, but I can't find any really convincing demos or reviews for using it as a small PA. I'm skeptical that it can hold up to even a small coffee shop venue scenario. Anyone actually try one of these with a KPA?
I'm not Paul (duh), but I have had extensive experience with the Bose, and I would go with the Bose. Any time you set up 2-speakers, you end up having a "null" at many frequencies between the 2-speakers. The ability of the Bose to give you perfect monitoring and a very wide sound-field is unique.
There is another post on this board - somewhere, or maybe TGP - where the poster asserts that the Bose mixer corrupts the sound....and that another, inexpensive mixer should be used instead. I've not tried that, but considering the price, the A/D/A converters couldn't be too robust, so he may well be correct.
As Paul said, the older Bose L1 has a built-in mixer,
I would suggest that you could buy one through Craigslist, try it out for a while, and sell it for what you paid for it if you didn't like it.