I have run my car with its jspec brakes to 158mph on the gauge and never had any issues pulling up on the Autobahn when the Polish wagon doing 50mph pulls out in front. The big brakes = better stopping power is largely a myth. Big discs just dissipate heat faster than smaller discs so can withstand repeated use longer before fade sets in. Multi pot brakes tend to reduce the effort required in braking more than stopping you in a shorter distance. So, unless you are planning to go track racing then you would probably not notice any difference beyond pedal feel with big brakes over small brakes and not actually reduce the stopping distance in a emergency braking situation appreciably.
More effective braking, as in shorter stopping distance, is tied much more to your tyre and brake pad selection/quality/newness that it is to big brake or small brake.