[BrianG]

That 1620A rating has a little footnote on it: "Transisotr's rating at 25 C˚ junction temp" (quoted with misspelling and all :)). I hate it when manufacturers rate things like that. What ESC have you ever felt runs at 25˚C? And that's the junction temp, not the case temp. The junction is probably at least 10-20˚C hotter than the case and there is quite a temp derating curve on some FETs. All it does is mislead the customer with inflated specs, as you said.