I don't think I'm using the built in indent for clojure.

I'd say that it is easier to extend the highlighting. Not necessarily a better highlighter

it's supposed to be significantly faster too right? not that I've seen slow syntax highlighting in vim the way I used to in emacs...

I did read there's still some performance issues in tree-sitter in a neovim commit/issue. I did notice that the indenter was slower than vim-sexp's. But that might be unrelated to highlighting.