I was looking at Pomelo. It's a nice framework, but I didn't notice any greater advantage than say Photon outside that Pomelo is free.
Pomelo seems to be really built around using javascript programming for server. Where as Photon was built around both EchoPeer and programmed servers.
It still seems to be an API above most C2 developers intended skill target. Otherwise it seemed pretty good if your a JS programmer.
I haven't used it. So I could be mistaken.