I've got the later 80-400 and at RIAT last year I couldn't get all of the A400 in the shot at 80mm when it was closest, even the Chinook filled the frame at 80mm when it was hovering near to our viewing field. Likewise when the Red's came over with the Vulcan I was using 80mm. I won't use a TC, so for wildlife i'd use the Sigma 150-600c, if it's airshow only I'd get the 80-400 if it's your one lens. I can't think that I missed many shots for reach especially as it was hot and the haze from the airfield was a minor issue at the long end.