You actually should at least consider some of them, like ZFS’ ARC. Also can you imagine ZFS’ dedup being useful !?
Assuming they work with qubes, of course. Not like I checked lol.
ARC should help with starting disposables (even if you don’t have enough ram you could try using a “lone PCIe 5.0x4 NVMe SSD” / RAID 0 - like setup for second level ARC) , while dedup might make cloning pretty much immediate.
I assume that nothing will help with backups that much, since you should store backup remotely / on a separate drive. Considering cloning and snapshots, do you intend to store some backups locally? If so, why? Just curious.
p.s. compression is more of an i/o speed and storage capacity for CPU work tradeoff. Use if you want to ditch efficiency in exchange for effectiveness (and have spare CPU cycles to work it)
p.p.s IMO mdadm is outdated, you could use lvm directly instead.
Also I heard that the main benefit of btrfs is their snapshots, but raid 5 and raid 6 support is kind of meh. But please, please check it yourself, I don’t want to ruin their reputation, and I haven’t tested it myself in a while (years)
It also seems like SSD write amplification is caused by incorrect ashift, but there is no experimental proof in the thread you link to. I spin rust, there would be no proof from me.