Whats the point of a higher mAh in racing?

[qatmix]

Hi All

decided to keep using nicads for now, so was just about to buy some 4600 stick packs when I thought what is the point?

These are for racing, and a race lasts 5 minutes, anything 2000mah and over is fine to power my brushless.. I just wonder why everyone seems to value the higher mAh? If I run 3300's they weigh around 90g less than the 4600's so it seems to me that as they output the same voltage etc over 5 minutes (obviously they would drop off sooner, but it makes no difference if its 10 mins or 20 mins) my car will be faster..

Am I missing something?