I know my own personal anecdote isn’t much, but I’ve noticed pretty good space savings on the order of like 100 GB from zstd compression and CoW on my personal disks with btrfs

As for the snapshots, things like LVM snapshots are pretty coarse, especially for someone like me where I run dm-crypt on top of LVM

I’d say zfs would be pretty well missed with its data integrity features. I’ve heard that btrfs is worse in that aspect, so given that btrfs saved my bacon with a dying ssd, I can only imagine what zfs does.