It's all about driving style.

See, in Japan drivers typically run higher rates in the front than the rear, High performance drivers go banzai into a corner, and trail brake, which induces oversteer as they scrub some speed and get back on the gas to power out of a corner. To say the least this will scare the bejeezus out of most American drivers.

In this country, we drive fast by being smooth and coaxing as much grip out of the tires as possible. We brake in a straight line usually, and then power through the corner much, much earlier than our typical Japanese counter-part. Since we enter the corner at a slower speed, we have to get the rear of the car to rotate until we get back on the gas, and so a higher rear spring rate will accomplish this. Turn into the corner, the rear rotates, and once you apply the gas, the weight transfer sticks the rear tires and you're launching off of the apex.

Which is faster? It depends on who is leading, since either driving style could disrupt the routine of the other in close cornering. On equal terms, I'm not sure you can find a noticable difference in lap times with skilled drivers using either method, it's more personal preference than anything.