I still say the biggest advantage for the average club racer about polishing the bottom comes from actually turning your boat over and spotting any cracks that might let in water, loose bailer that not functioning properly, or something else that needs repairing. The actual speed advantage is easily lost by a single bad tack on the course, having a polished bottom might be meaningful at the elite level, but not the rest of us.A shiny, polished hull isn't necessarily fast. However, it definitely will have a gleam when it reflects the sunlight. The guy watching the starting line is SURE to see you over early.
But I'm probably going to use some Starbrite on my boat anyway.