Interesting discussion so far. I particularly like the idea of a 'new session' as suggested above. This would be worth more discussion and ideas. As you say, maybe a session with four (ish) 'acts' per evening, with a balance between 'singers acts' and instrumental acts, giving each act say half an hour could make for a very enjoyable evening. Between 8 and 11 you could get six acts in. The acts would depend on the organisers. Maybe performers would have to 'book in advance'. I can already see the organisational problems, but it's worth thinking about...