YMMV. Manjaro's broken on me multiple times. I leave a machine alone for two years and it's next upgrade is almost guaranteed to break something.
Here's one of the oldest versions of the "Arch-based distributions" page on the wiki. It has a notice at the top that says that forks are not supported by the community or developers: https://wiki.archlinux.org/index.php?title=Arch-based_distri...
The only (real but small) difference is between desktop environments and their choice of default apps (eg. file manager).