@Daniele Changing gateway type will not impact your data/settings. I hope you are changing the gateway, the underlying node structure will remain the same.
I recommend taking a backup prior to this action.
If you ask whether I have included my own scripts: No.
It is just a "virgin install" without any customizations.
The four fields displayed in the GUI under Utilities- HTML additional headersare all empty.
Edit: Oh, and if some testing on old hardware should be required, no problem! I will be happy to try things out. The only limiting factor might be my little to non-existing programming skills