I did the same thing but I'm now pushing it a bit further: POSIX shell rather than Bash for scripts. If what I'm doing can't be done with that it suggests that I should probably just write it in Python or Perl instead.

Fish scripting is limited to functions/aliases and this works out well since they're easy to read and tweak over time.

that's a sensible approach. fish does have the best interactive interface out there. i switched to elvish because i like it better for complex commandlines, mainly because it has support for more advanced data structures and also integrates json well. (and i realized that using braces for code blocks is nicer in a complex one line command, but both are better than bash for interactive use)

Really like using fish as my interactive shell too.