any hints?
yes, Raknet. It already has features for syncing that would make delta-timing based on server vs client ticktime differences easy, and also supports reliable udp among many other things. Not to mention, there's an entire community that you can get support for it, rather then the few here who actually like or use gnet.
Even though I wrote an enet module that worked fairly well, I still have a lot against enet (+gnet) due to the fact they have so many missing features that led me to dead-ends constantly - not something you want to wrap your head around for a year before perfecting what you want or need for your app/engine.
Just a suggestion that i'm thinking would save you a lot of brain aches.