From reading battery tests/shootouts and having owned a few lipos myself over the last 4 years or so, I really don't think C ratings mean much at all. They definitely aren't an objective standard that will let you compare batteries between brands. For example, a Turnigy 60C battery isn't better than a MaxAmps 40C battery. At best, C ratings will let you compare batteries within a manufacturer to get the performance you need. I don't know of any appropriately powered models that would go over 20c continuous current, so the ratings aren't useful for determining firm limits of power consumption. But on the higher performance models where you are only planning to get 5-6 minutes of full throttle flight time, you may see a power increase by going up to the next C rating level due to the lower internal resistance.