I don't have much experience with btrfs but my understanding is whilst they're generally equivalent the multi-disk config of btrfs isn't really considered stable (think raid5/6 vs zraid1/2). Most production use case is single disk.
Regarding performance, I'm guessing you won't be happy with either if you're not happy with performance. You want to be looking at ARC / SLOG if you want higher performance.
Using the built-in RAID of btrfs is unstable in some cases, but you can still use btrfs without using its RAID on top of mdadm with that providing the RAID, like ReadyNAS and Synology NAS devices have been using by default for years.
thanks for the input -- so yeah I saw the RAID5/6 thing. I'm wondering if it's a bit of a moot point, because the servers basically all come with 2 identical drives of various speed.
Moving writes to ARC or SLOG-on-a-faster-thing would also definitely help, but I'm dealing with SSDs for the most part.
Also, talking of faster storage, NVMe looks really bad for ZFS (and probably btrfs), based on this reddit post[0](graphs[1]). It's not terrible of course, and some recommended that maybe actually turning ARC off would be better, since it might have been actually getting in the way of the NVMe drive.
Regarding performance, I'm guessing you won't be happy with either if you're not happy with performance. You want to be looking at ARC / SLOG if you want higher performance.
https://www.growse.com/2020/06/09/improving-zfs-write-perfor...