They are not all made equally
I had both of them out yesterday. The yellow one didn't eve have a full charge, yet was notably faster than the green one. This was the second run for the yellow one and the first run for the green one. Maybe the motor in the green one needed a little breaking in. I doubt it.

Battery
Come to find out, the included battery is actually for the Firebird XL, thus is not sealed well enough. Water gets in and rusts the connector plates. The batteries are fairly well wrapped. I'm going to fill the ends with silicone sealant. That should do the job.

The Scoop
Each boat comes with 3 rubber balls for bouys and a light plastic scoop or cowl for manipulating the balls. Put the scoop on and leave it on. It doesn't affect the boats performance one bit, bit has many advantages. It retreives the ball (it's entended use), acts as a good bumper, and helps keep the bot from getting stuck against the side of the pool.

Water Soccer
I plan on playing this very soon. Yesterday, I just chunked all 6 the balls into the pool to see how quickly I could retreive them all. I learned a very interesting thing that will come into play when soccer is played. You can only go about 1/3 throttle with the ball. Go any faster and the ball will flip out of the cowl or the boat will ride over the ball. Either way, you'll loose the ball.