I can definitely tell the difference on a motorcycle.
I raced a few times on my stock rotors on my 07 R6, and then got Galfer wave rotors
(here's a pic from my bike)
The difference was after the first couple laps, I would have to press the front brake very hard and get little response with the stock rotors, It took an additional 30 to 50 feet to come to the same slower speed, as apposed to the wave rotors. I would race 20 minute sessions on the wave rotors and not one time have to slow down earlier to make up for the lack of stopping ability.
granted its not scientific proof, but i know it does work. I dont have proof, but hopefully this will help you make up your mind.