Hey Stuart! That's a nice result! I'm afraid though I think part of the reason for the softness is that you captured for too long.
90s should be your maximum capture length for Jupiter, and at 5fps that only gives you 450 frames. To get 2000 frames you've captured for way longer and the stacking will blur some of the features due to the rotation of the planet.
I'm sure the other part of the softness is due to the low altitude that Joop would've been before midnight. Still, a nice result! Well done.
I did a quick split, LR deconvolution (3@1.1) and recombine, it generally helps restore the correct colour balance. It obviously introduced some nasty artifacts because the image was already comperssed, but you get the idea
Hope you don't mind.