Underdrive Pulley: Useless?

conquistador

I was chatting with my father (a long time Porsche tech) about my next mod--which was UD Stillen pulley-- and he said it didn't free up any power. He said it was completely useless to underdrive the accessories because 1. when you're going in a straight line or dyno'ing you're not putting the power steering under a load, 2. when you're battery is fully charged there is very little load on the alternator, and 3. if you're A/C if off you don't have the AC clutch engaged and the pump is under little to no load.

These accessories are basically free spinning and drain very little power from the system so why waste money on an UD pulley?

Got me thinking...