Hi all,
I use the S1 Pro mainly as a keyboard monitor, and for its size and weight it is very impressive. You get a full-bodied, loud and clean sound, which works for all sorts of rooms and podiums (pub, small club, large club, up to small festival podiums). I certainly would go a play small solo gigs with the S1 Pro, too.
The build quality is very good, the whole system is super easy to use, and the only thing missing on my personal wishlist is an XLR output.
All of the above makes the price for the Bose S1 Pro pretty reasonable - I rather have one system like this than one or two "cheaper" speakers which always will sound like a bad compromise.