The extra cooling on the Max3 could potentially give it a higher stable speed when overclocking but from the results that I have seen on the forum the only difference between the two boards is features.
They use the same chipset, the only difference is the features on the board and some extra cooling. With that, it would be just about impossible for there to be a performance difference between the two boards. Like I mentioned before there could be a difference in overclocking capability which would then effect the end performance result but even that has not been demonstrated consistently. Both boards seem equally capable of running at high FSB speeds, my own IC7-G running at 300mhz FSB.