The problem is though, that the last time I've checked, it was excessively simple- it didn't support individual files selection.
From what I can remember, a lot of the slowness came from GPG, and specifically files being compressed before encryption. Disabling compression speeds things up, but trades off disk space (and security).
I wonder what it'd take to reengineer the thing to take advantage of multicore -- being CPU-bound on a single core is I think what makes it slow.
It is a bit unclear if you haven't been looking at other snapshot management utilities. Many other tools have various dependencies which may or may not work on your chosen operating system.
So generally the requirements are:
- ZFS running on the volume you want to snapshot
- Bourne shell
- Gregorian calendar
As far as OS X goes, I'm not sure how many people run ZFS in production but I know there were some people working on it. I've never used it but it still seems to be updated: https://github.com/openzfsonosx/zfs