ASG 120 Home Licence upgrade to v9

Hi All,
I hope you can help me. I have an ASG120 (One of the new Sophos ones) running 8.308 with a home licence and would like to upgrade to v9 but when I go to the "Upgrade to UTM 9" tab it says:

"A product upgrade to version 9 is available. However, due to the complexity of supporting all kinds of hardware that are currently running ASG Version 8, an automatic upgrade is only available for Astaro Hardware Appliances."

I got the ASG120 to accept the home licence by renaming /etc/asg to /etc/asg.bak is it just a case of:

1) Backing up my config
2) Renaming asg.bak to asg
3) Running the v9 upgrade
4) Renaming asg to asg.bak
5) Restoring my config

Would this work? Has anyone got any experience of this?

Thank in advance

Karl