About once a month I give a try to LSP in Spacemacs and get bummed that it impolitely overrides CIDER's behavior with describe-thing-at-point and cursor hover 😞

This isn't LSP's fault, it's just Spacemacs' behavior

Is this one key binding definition in the Clojure layer your only concern?

not just the key binding, also the display at the bottom frame when the cursor hovers over symbols

Generally I'd want to keep all of Clojure layer's bindings unchanged

I only recall that one changed key binding. LSP does add its own keybindings along side the Cider and clj-refactor key bindings (I have used clj-refactor for years, so theyay be some over-riding there)

Presumably

"hh" 'cider-doc
              "=r" 'cider-format-region
              "ge" 'cider-jump-to-compilation-error
              "gr" 'cider-find-resource
              "gs" 'cider-browse-spec
              "gS" 'cider-browse-spec-all))

and mr

LSP by nature adds a lot of common language features, some of which CIDER also implemented. They are both self-described IDEs so bound to be some crossover. LSP is a big change to Emacs UI (although more features in the UI are now switched off by default). Unless there are specific LSP features needed, stick with Cider and clj-kondo