It's a steep price to pay for either this or the higher model, but I might bite and force myself. Can't imagine what macro or even birds in extreme slow mo would look especially with some of the cheap yet good TTArtisan 500mm F6.3 manual focus (750mm). The 2K can look good with DVR 2x upscaling.
what makes the 2k unusable vs 4k, i guess you just said it didnt look good instead of going into detail. It didnt look terrible to me but just looked like how it would when you cut halfway down on resolution is all
The aliasing/moire is pretty bad in 2K when filming fine detail things. You maybe able to shoot around it if you use a softening filter or stick to shallow DOC shots.