Spacers for the cassette to the hub or spacers between the cogs? Yes the spacers for the spacing of the cassette to the hub might be the same depending exactly on what your free hub body length is, but the spacing between the cogs is unlikely to be the same between the various 9, 10 or 11. Shimano only shows the 11 speed being compatible with other 11 speed components. And likely the same for any others.

But I just did a hasty check on Shimano's tech doc site. I'd never heard of CUES before.

What is it that appeals to you about it? Are you wearing out your other cassettes?