Looks interesting, thanks for writing and posting.

I would suggest you go further and package all the branch related operations as subcommands of "gut branch". For instance, "gut branch ls" is more transparent and explicit than just "gut branch".

Also move the "switch" commands to "branch". Force branch creation to be explicit ("gut branch new") that does not change the current branch. That will prevent typos or memory lapses from leading to errant new branches. Then provide "gut branch switch branchname" that will only switch to an existing branch. You can include a "-f" flag to explicitly force branch creation, allowing a single command "create and switch" operation. You have in general avoided flags, but "-f" is extremely common and widely understood in the unix world.

Small changes like these can make significant improvements in the ergonomics of an interface that is already better than git's.