I've been doing a photo back drop at the New Years Eve dance at the Expo Center in Valparaiso for over twelve years. Usually I stop shooting at some point. Download/edit the photos and the guests can pick up the prints at the end of the night. Since I charged the guests, they had to pay up front and I had to keep track of what they wanted. I also had to bring a laptop and printer along.
This year I used my new Social Booth. I charged the Expo Center a flat fee for unlimited prints. What a difference! The guests got their prints right away and they could come up as often as they wanted. I did post the photos the following day so they could order additional or larger prints if they wished. There we almost four hundred guests so we had a busy four hours.