The big difference UX wise between chatbots and Surf is that Surf is built entirely on editable documents that you can mold / craft into an output (vs chat).

We actually had a chatbot, but our explorations showed that notes were a more effective in many cases!

An example of local data is that "Applets" made in Surf can be opened / updated from your local code editor, they're just HTML files.

Umm -- not being tied to ChatGPT? Like, that's huge. I personally do not consider consistently using any AI tool unless it has a local option. I've been air-quotes "paranoid" about things like this my whole life and it's served me QUITE well.