BTRFS can work across multiple disks much like ZFS. It supports RAID 0/1/10 but I can’t tell you about performance relative to ZFS.
Just be sure you do NOT use BTRFS’s RAID5/6. It’s notoriously buggy and even the official docs warn that it is only for testing/development purposes. See https://btrfs.readthedocs.io/en/latest/btrfs-man5.html#raid56-status-and-recommended-practices
Edit: Another interesting thing to note between the two file systems is deduplication. ZFS supports automatic deduplication (although it requires a lot of memory). BTRFS supports deduplication but does not have built-in automatic dedup. You can use external tools to perform either file-level or block-level deduplication on BTRFS volumes: https://btrfs.readthedocs.io/en/latest/Deduplication.html
Related feature on my wish list: I’d love a way to basically fork a feed based on regex pattern matching. This would be useful for some premium feeds that lump multiple podcasts together. For example, one of my Patreon feeds includes three shows: the ad-free main feed, the first-tier weekly premium feed, and the second-tier monthly premium feed.
I don’t want to filter them out because I DO want to listen to all of them, but for organizational purposes I don’t want them lumped together. I’d prefer to display these as two or three separate podcasts in my display.
Another example is the Maximum Fun premium BoCo feed. They include the bonus content for ALL their shows (which is…a lot) in a single feed. I only listen to about half a dozen, and even that is a bit of a mess in one feed!