It seems that when changing the stable/beta channel it applies for all projects rather than being project specific (despite being in the Project Assets Updater window)
I am constantly switching between old projects that need to stay stable and new ones while trying to work with AC2 in beta - it is a real PITA at the moment as I have to then go in and change the channel each time I switch and there is a high risk that I click the wrong button and accidentally update a project that is not ready for AC2