In the end the better driver, even with lesser equiptment will most of the time win. But with even drivers and motor, more voltage will produce better top end, period. If you can pull the next guy by 5 or 10 feet on the straight, given equal driving...you know what the result will be. And I can absolutely tell the difference between a 1.15v 3300 and a 1.24v 4200. I know it only takes 1 or 2 bobbles to negate any advantage, but all things equal, I would want more voltage.
Oh, and the question earlier to the mini veterans...hopefully didn't come off wrong..I do truley value all your opinions.