Looked up 'Hover' in the dictionary. The definition is ----

To remain or linger in or near a place

or

To remain floating, suspended, or fluttering in the air

I guess for airplanes, you would have to add that the aircraft was supported only by the thrust of the engine.

If the above is true, then the comments about pulling out vertically from the hover, and comments about 5secs not being a hover are really moot points. While duration and vertical pullout may make for a more impressive feat, they don't define or refute a maneuver as being a true hover......

With all that in mind, I can't say that I have seen Kirby hover, however I have seen him do some really impressive harriers and tailsliding torque rolls. I have some video of the TurboRaven, but I don't remember it hovering in any of them, but he does do some really impressive 'up' lines in it.