Both openSUSE and [as of very recently] Fedora use btrfs by default, so btrfs support seems pretty stable these days.
(But as others have pointed out, there are options for using zfs on linux, too)
(But as others have pointed out, there are options for using zfs on linux, too)
1. It often happens that the main repo offers a new kernel, but the corresponding module is not ready on obs yet. This means upgrading to the latest rolling release cannot just happen at any time, but requires careful planning. This is a big inconvenience.
2. In the past dracut sometimes just failed to pick up the module for the initrd, causing a boot failure at the next system start. I could not figure out why, however this never happened with the first class supported ext/xfs.
3. The distro's boot/rescue media do not contain the driver. This means a third-party boot medium is required to go into a broken system, and repairing it when chroot is involved is now much more complicated because of the different distro.