I've been using Bose S1 Pro System for the whole summer now. I started to use it as streetplaying amplifier, significantly boosting my performance on the street. Approximately it gives you 100 meters of audification on the street, to the both directions. At home, I use it to play backing tracks and just plug in my acoustic so I can jam with it.
On troubadour gigs it works well as a monitor, especially with the Bose model 2 tower. Clear sound is especially good for hearing your tune on singing. Only place where it starts to lack punch, is when you have 2 or more singers on the stage, and also more acoustic guitars. Still it works fine on solo gigs.
About the sound. It has strong middle, clear highs and sometimes even too much bottom. Especially with rich toned acoustic guitars you have to cut the bottom so it doesn't start to hum. I do not see this as a problem, more as a feature and it is quickly eq'd or cutted out if needed. When you play beach volley with your friends, you really want to get that bass boom for Uptown funk.
It is a portable, realiable and very efficient speaker. I'm getting another one, so I can test em out together. Less of carrying stuff, more playing!