Thanks for your feedback!
I would like to add that we also used Sametime for the event:
The "Digital Week Info Desk" and the "Sametime Coffe Breaks", which were are open all day and where you could just walk in and ask questions, were all using Sametime 11.5 meetings. Some attendees even kept multiple browser tabs open all the time and so they could simply hop between Sametime meetings without the need to authenticate or type in a name. This worked seamlessly, literally like walking from one room to another in an on site event.