There is no international standard for C ratings, some companies quote the burst rating and others the constant current. For the most part, C ratings fall in the clever marketing section, but they are of value up to a degree. What I mean by this is, once the motor cannot pull anymore current at the supplied voltage any C ratings above this current value means nothing.

Then there is temperature, some say a warmer pack supplies more punch, so a lower C rating battery can feel punchier then a higher one. The beauty of LIPO racing is the playing field is much more leveled than with NiMh, I would not worry to much about C ratings but I would buy from reputable sources.

my 2c.