Go Spektrum, you will never regret it

No interference form you on-board equipment especially electric motors.
No waiting for the frequency
No one switching on and causing you interference

No trying to fine a place for that long receiver aerial
but i would recommend at least a 6i as it gives you more functionality with things like mixers (mix one channel to another) for use with things like twin props....
I have used spektrum for several years and have NEVER had problems and I also have come from the Airplane/helicopter and TURBINE jet world. if its good at 200mph its good for boats and have never had a problem with it in boats.
Also Spektrum receivers are cheaper than FUBAR receivers....
Mark