I have been trying to get onto the demo site but its dead - this is the error i get

502 Bad Gateway

Thank you. Fixing now. It's weird nginx issue that we are aware of, but still looking for a solution.

Any info re updating from Apache to Nginx?

Update to nginx was a right choice, but we're still learning. We plan to write a tutorial on how to "speed-up" Dolphin on server side and that willl include nginx tips.