Hey Sam, glad you enjoyed the post!
That’s a great point about ram requirements, I’ll add a note about that.
As far as expanding ZFS pools, all my experience with both file systems was for home use, so I just went with mirrors on both ZFS and Storage Spaces. With mirrors the two aren’t very different in terms of difficulty in growing a pool. With ZFS you have to add a new mirror pair in a new vdev, and with Storage Spaces it’s basically the same.
Also, thanks for sharing the info about performance, I didn’t know that. Do you have any sources on that that I can link to in the post?