[Patrick]

Have you read everything people have said about total watts being most important to runtime and power output, not amps or volts by themselves?
I guess I'll explain it again. 6s has 50% more voltage than 4s, so to have the same power output on 4s you need 50% more amps.
Example for 6s, 22.2 volts X 10 amps will be 222 watts
on 4s, 14.8 volts X 15 amps = 222 watts. An extra 5 amps to make the same power.
That means a 4s setup should draw 50% more mah per minute than an 6s setup of the same speed and power.
Your 6s current draw you say was 160 mah per minute, so 50% will be 80 mah.
160 + 80 = 240 mah per minute for a 4s setup of the same speed and power, which is pretty close to the 250 mahs that you got. Now you have seen the real world difference between high and low voltage that people have been talking about all this time.