cheeeeee I'm sorry to join the thread so late - I'm mostly at PW, but sometimes check in here as well. With my family, I attended the concert in the Bösendorfer Salon! The audience numbered perhaps 20 in total - very intimate. It was great, especially the Chopin Scherzo no.3 by Strata and the Gaspard de la nuit by Kim stand out clearly in my memory.
Interestingly, my sons and I also went by the Bösendorfer Salon a few days before and tried out the actual 280VC, that the concert was played on. Quite an instrument!
I remember a small group of people standing outside the Salon when we left - I must have passed you on the way out.