Side note, since it's probably a niche use-case, but using NVMe's in Z1 was both pretty effective with VMs and cheap enough on usable capacity (4×1TB for ~3TB usable).
I feel SSDs are in a totally different category that makes Z1 an actual option, whereas I don't trust it for spinners. Key difference being that a failed SSD can usually be read (only) whereas a failed spinner is usually as good as bricked.
I use SATA ssds in RAIDZ2, and have 6*1TB for approx 4TB usable. They're fantastic and I have yet to have an issue replacing a drive. Nor do I need to do it very often as my workloads are pretty low, it's mostly an archival box.
It's been great, right up until one of the sticks of RAM started to fail...
I feel SSDs are in a totally different category that makes Z1 an actual option, whereas I don't trust it for spinners. Key difference being that a failed SSD can usually be read (only) whereas a failed spinner is usually as good as bricked.