Another 'Cube' fan here . :)
I do most of my practicing - and impromptu playing to people , on my much loved Micro-Cube. As I was most impressed with it, I managed to 'score' a Cube 60 for backup to the main Jazz rig.
For mellow Jazz, the Micro cube would be good enough to 'play out' with, in a small room. It's built like a tank ( as the Cubes are ) - and even merited me buying it's own carry case / cover. The batteries seem to last a long time too, I'm still on my first set many months later.
My favourite settings for Mellow Jazz on the Micro-cube being :
Amp : 'JC Clean' , Tone at 3 o'clock, Reverb at 3 0'clock, Gain at 9 'clock, Volume at 3 0'clock.
Great stuff ! :)