My quick scan of the literature out on the Credo series doesn't directly address the capacity of the battery.
I understand exact answers are probably out but...
How long can you shoot for? What happens in the middle of a shoot out in the middle of nowhere and the battery runs out of juice? With an external you just have to pop on another one and continue on. Can you externally power it from another battery? What is the expected lifespan of the battery and is the replacement by the user possible or does it need to be sent in the Leaf? How long does it take to recharge?