Yes, for reasons that would pollute this thread, we're running a number of single host pools.
The broader picture is:
We drive https://github.com/ddelnano/packer-plugin-xenserver from a CI server to build a small number of base images / templates
A related CI job then replicates those to all destination pools.
I don't think I'm yet in a position to share full details publicly, but if you're interested I'm sure I could give you more visibility to what we've built so far, and our intended direction of travel.