If you are using stock Beetle brakes and change the mass distribution (by changing the body style, for example), this is true, and has resulted in heavy custom bumpers to try and redress the balance. The first Porkie 911 had 20lb of lead moulded into the front bumpers.
The solution is balance - don't try and change the mass distribution to suit the standard brake bias, change the brake bias to suit the new mass distribution.
Paddy's disc/drum brakes, if left as standard, will not stop his lighter car faster than a stock Beetle, because the front wheels will lock up instantly, and using less pedal pressure will maintain control but produce less retardation. But with a balance bar and the same set-up, the bias can be adjusted so that the front wheels lock ever-so-slightly before the rears, allowing the full pedal pressure to be used. Paddy's lighter car now stops more quickly with the standard brakes than the Beetle ever could!
One thing you will find is that you will need to dial in more bias towards the rear of the car to get this optimum balance. This means the rear brakes will be working a lot harder than they did before, and a disc brake conversion will improve the efficiency, as well as reducing fade effects.
But the key to efficient braking is balance.
Lauren