2001 used all in-camera composites, to the best of my knowledge. And that film holds up beautifully on Blu-ray. All the "motion control" rigs were mechanical, too. Now that's impressive.
By now I can't even guess at the number of times I've scrutinized 2001 on laserdisc and dvd and BR (not counting nearly two dozen theater screenings.)
Even the stuff that is done in a way that should feel at least a little clunky, like all the still-photo cutouts, is just executed with such finesse that you marvel over & over.
I know Trumbull always thought that not being able to change speeds of the ships during the shots was limiting, but I think the film absolutely makes a virtue of that with the ballet approach ... if you had a space pod ripping through frame it'd be like seeing a breakdancer in a Fred&Ginger flick.