I have an IWC Portuguese Chrono with the 7750 movement that had a particularly annoying whirrrrr sound. You could hear the rotor turn from 10 feet away, and every 10 minutes or so it would go nuts; it sounded like a tightly wound spring was unwinding inside the case. I love the looks of the watch, but the sound was so annoying that I never wore it. I would have been embarassed if someone had heard that incredibly loud sound. But from reading the forum, it seems as though my watch had much more noise than the typical rotor noise that people talk about with this movement.
Anyway, I read the thread mentioned earlier about how to fix the noise by applying axle grease to the rotor. I was going to go ahead and give it a try. I figured that since I never wore the watch because of the sound, there was little risk to me. But The Zigmeister cautioned against it. So I took an alternative route: I bought some high-grade all purpose watch oil (Moebius synt-a-lube 9010) on ebay for about fifteen bucks and put a half-drop on the rotor. My assumption was that this would be less dangerous than using axle grease.
Well, it worked beautifully for me. The rotor is almost entirely silent now. You can only hear the whirr if it is by your ear, and the "unwinding spring" sound is completely gone. The watch is on my wrist as I type this. So for me, that was a great fix and well worth the money I paid for the oil. I now wear the watch regularly.