We've finally got some water back into our pond,(yippee),so I tried out the boat today,and the modified rudder works a treat. On 3700mAh packs,I'm getting around 15-20 mins runtime,even on full throttle,so I'm extremely happy with that. She runs well in excess of walking pace,and even at a jog,you're hard pushed to keep up with it,so as far as I'm concerned,there's no need to change the motors in her.
The only real downside to the boat,is that there's no reverse,not that my ESC doesn't supply it,but rather that the props are one-way only,and can't move the boat backwards.They make great brakes though. I forgot to take my camera with me today though,so no vids unfortunately,but I'll get some during the week.
All in all,I'm very pleased with the performance of this modified RTR.