*lol* Yeah, 6’5″ should be big enough 😉
Problem is, software solutions are just guessing when they try to create frames that are not in the original footage.
Those warping artifacts are a result of this “guessing-method”.
When I wrote “small moving objects” then I didn’t refer to you as moving object in the first place, but to all the little details, even those in the background, shadows etc. The software doesn’t know, which part of the footage is the “essential” part (i.e. “you”), it just recognizes diffences between frames. So higher shutterspeeds create a better “contrast” between frames and makes it easier for the software to guess.
1/250 is quite high – so could be enough. Or not. 😉 The faster the motion, the higher the shutterspeed for better results.
And of course there is a limit. Slowing down 100% should be no big deal. Even 150% is possible sometimes. To my experience 200% or slower introduces artifacs. But this differs from footage to footage.
One solution might be treat background and foreground differently, so to roto the moving object (i.e. you), save the clip uncompressed with an alpha channel and slow this “foreground element” down and then comp it with a cleaned-up and slowed down (mybe just a still?) background element. Will be time consuming, but might work.
hth