Yeah, I know what you were referring to. I have the 3000 grit foam trizect already. But it was going by hand. I could see a difference. I'm going to pick up some for the pneumatic once I finish sanding. I just wondered if you'd tried it with speed on a gelcoat. The grits available (that I can find here) are all the high-end 3m Trizect finishing discs. While they do cut and do a great job. They don't last very long. It took me 8 just to do the bottom front half of the boat. And at $3 a pad, that's pricey.
Currently I'm doing the bottom hull. It was so bad I had to start with 600 grit, then 1000 grit, 1200, 2000 (by hand), and then 3000 grit foam on the pneumatic. Then compound, polish, and buff.