RE: Higher C advantages and disadvantages
Just because a battery is 40c capable doesn't mean that its going to burn anything up if your setup doesn't demand it.
If you're setup is trying to over pull a 20c battery it will puff up the battery and possibly catch fire. That doesn't mean if you up the C rating on the battery you're going to burn anything up. Actually the battery will just run cooler and last longer (cycles, not flight time)
Upping the C rating does NOT effect flight time. Using more amps effects flight time.