yes, was debating geting some (cheap lightly used)da carbon clichers from 10/11 speed era, but web trawls say cassette spilines are diff , so will probably plumb for cosmics
I think only the WH-7800 range got the deep spline 10-speed-only aluminium cassette rotor, it was quickly replaced by the 7850 with the standard HG spline Ti rotor, which carried over to 7900. WH-9000s are for 11-speed but can take any other HG cassette (7/8/9/10-speed) with appropriate spacers to fill up the gap.
I think only the WH-7800 range got the deep spline 10-speed-only aluminium cassette rotor, it was quickly replaced by the 7850 with the standard HG spline Ti rotor, which carried over to 7900. WH-9000s are for 11-speed but can take any other HG cassette (7/8/9/10-speed) with appropriate spacers to fill up the gap.