Yes, there is a catch, if the proxy works as stated, then what happens if you have more than 65535 end users? I can't imagine whoever built this has a farm of load balancers, or multiple networks for this to work. Honestly, this sounds like a standard proxy. If you are trying to advertise something, you better present something more than a couple of paragraphs, and a picture that makes it look like the process is complicated. I still believe Tor is much more effective for anonymity, as Tor is peer to peer, and ever corresponding point acts as a gateway to the next. I fail to see how JonDo is a complicated process, when you use one server, and some fancy encryption methods. There's still a single point of failure, and if you are slapped with a subpoena you will be forced to hand over your customer's credentials anyway.
