Here is my boat build. It's been through a couple ESCs, several steering nozzles, 3 servos, etc..
I'm using a 3700kv boat motor
http://www.hobbyking.com/hobbyking/s..._Inrunner.html
50a birdie ESC
cheap orange servo from hobbyking stuck in a balloon and mounted with a custom steel plate
Overall this boat performs great, a different motor setup would probably gain some top end speed on smooth water. I use it mainly for river and creek runs so the tourqy 3700 motor is great for me. I've been through a lot of trial and error and can probably answer some questions if anyone has any.