I think I'll give my opinion about each version. -the ones with black and white: The black side is ok except for the dark blue node marker. The white side is not my thing because the yellow and light blue or light colors are difficult to distinguish in my case. -Black and grey navballs: I think these are very good, but the dark blue node marker is the hardest thing to distinguish, both on the black side and the grey side. -Entirely black with yellowish numbers on one side and blueish on the other side: This one is for now my favourite, except that I'd make the colors of the numbers and lines a bit more different in tone from one to another myself, but it's not bad. the problem once more is the dark blue node marker for maneuvers. The antimaneuver marker and the other markers as far as they are a light color, they are easy to see. The best solution for me in my case is using dark backgrounds, light colors for lines and numbers and light colors too for markers, but the problem is the marker's can't be changed as far as I know. So yes, right now I'm using the dark on both sides with yellowish and blueish numbers and lines, It's the one that fits me most. The ones with a grey part are not bad too, I'd also use them, but the one that gives me trouble is the ones with white background, just for light color markers. I guess everyone has a diferent issue and colorblindness in it's own can manifest in different forms, that's why the best option would be to let us be able to pick the colors that we want for every element in the navball, backgrounds, lines, markers.And I'd even suggest letting us change the form of the different markers, so we could distinguis them even if they were of the same color.