We went by Ryan Air to Germany and sent our kit over with those good peeps on Quake taking a roadtrip to Polland or somewhere. Thankfully, Quake found their way eventually and also kindly took our kit home with them too.
Now, I've never had any probs with airlines and paintball kit, so when I realised we had forgot to send a spare air system back with Quake, I wasn't too worried. I put it in my bag, reg on, and flew home. No problems.
Everyone makes too big of a deal about flying with paintball equipment. It isn't illegal... we are doing nothing wrong.
The only thing with Ryan Air is the stupidly low weight allowance on baggage. Pack light.