I never said 3 x .75" would cool better than 2 x 1.5"
He was saying the flow through the rad was the most important aspect and I disagree. I say that all the variables are important but you will get no heat transfer without surface area so IMHO fin count is the most important variable as that is 100% responsible for the heat transfer, the more fins per inch the more contact area between the tubes and the fins, the more heat can be transfered .
