RE: Expensive US made vs Chinese Batteries
The "C" rating is the batteries discharge rate. Meaning the 50C battery can stand more amp draw from the motor than the 25C battery. That does not necessarily relate to more "punch" as you put it. Your motor draws X amount of amps when it is running. If your motor draws less amps than the smaller battery is rated for then the larger battery will not make any difference. The motor always draws the same amount.
In other words your motor "requests" X amount of amps from the battery.
For example. Lets say your motor needs 20 amps to run. It will draw 20 amps from the battery. If your 25C battery can supply 20 amps your OK. If you connect your 50C battery, the motor is still only going to "Request" 20 amps.
Kind of like going to the bank to draw out $20.00 cause thats all you need. If you have $20.00 in your account your good. But, if you have $50.00 in your account, you are still only going to take out $20.00 cause thats all you need.