It seems like I'm selling my BOSE SOUNDDOCK 10, which I call a PA system due to its room-shaking qualities.
Having run a comparison with the HK Nano 300 again today, I come to the conclusion that the Nano 300 subwoofer does put out considerably more vibrating bass, and even if the Nano is not so brilliant, the stereo width with the 2 top speakers is better than that of the Sounddock 10. There is not much difference in weight. Originally I wanted to sell the Nano, but this is the more professional alternative.
Anyone who lives near my region (NRW) and might be interested to pick it up: it IS a serious mini PA with high output (louder than Bang & Olufsen A8), surprisingly good, deep bass (it has a built-in 6.5' vibration-absorbed subwoofer) and brilliant mid and high frequencies. My unit has hardly been used at all, I still have the invoice from about 2 years ago.