Can you use third party plugins in Sunday Guitar?
Can you swap out MainStage plugins for others like replacing SilverVerb with ValhallaVintageVerb?
It's a bit more complex due to the Sunday Guitar Board Builder and being able to swap out pedals on the fly, multiple channel strips/buses per pedal, so that is where the issues I think would show up. Amps should be an easy swap though since they are more concrete. You can always delete everything though and keep the clean workspace layout and customize everything how you want so its a good way to learn some more advanced MainStage mappings and controls. Just make sure you have a backup before changing things.