Well, he's clearly not a good rider (two, three stucks - just in that video!), nor a resident forum expert, so no way could he be right about 8200 RPM giving him the best results. Polaris obviously designed the engine to spin to at least 9k (why do you think they put a lighter crankshaft in it?), and even gave you a warranty for when you blow up a motor or three. Only an idiot holds onto a sled out of warranty anyway, and Polaris knew what they were doing when they cut the warranty for the 9R. Who wants to be caught riding last years model, amiright? And when you come across someone on the same sled, keep the old "bet I'm turning 400 RPM more than you" in your back pocket!
That said, run whatever works for you, and if it holds up, it holds up. Can't say I want to be the guy buying a used sled off Chilly, but then I only know a few guys I'd actually want to buy from (lucked out finding my current sled).