I've also always disliked the en_US.UTF-8 sorting. Personally, I use LC_COLLATE=C and keep the other locale settings to en_US.UTF-8.
I've used casync in certain use cases. It fits in nicely between a full backup solution and rsync/git.
I've also always disliked the en_US.UTF-8 sorting. Personally, I use LC_COLLATE=C and keep the other locale settings to en_US.UTF-8.