Phoinix, summer days in Colorado flatlands are often above 8,000ft DA. We land our 300c's up to 10,000ft DA. Other copters in class that outperform? A turbo B47 or, of course, a turbo Enstrom 280 model. I regularly land our Enstrom 280fx above 12,000ft MSL. POH lists HIGE up to 13,600. Hard to beat the EN28 for high altitude piston performance. Direct operating costs comparable to the 300c.