Hi Nick,
Glad to be of help! 🙂
I'm not sure what version is currently shipping from manufacturing unfortunately. I suspect it will be a 10.x version, so it should be straightforward to downgrade.
When downgrading ZD FW to a version that hasn't previously run on the ZD it will perform a factory-reset, obviously this won't be an issue for you on a brand new device.
All the best,
Darrel.