Not that will in any way settle this debate, in fact, probably the reverse, but you can find out if more or less pressure is faster in your tires by "brushing" with a friend.
Start out coasting eat the same speed, next to each other on a nice down hill. Then repeat with more or less pressure in your tires, and no change to your friend's. Similarly, keep the weights, positions, etc. unchanged from trial to trial. You should be able to see the effect easily. You can call sprinting back up the hill for another run "intervals."