I think it would be useful to be able to tell Sync to sync all of an extension's simple-prefs with a single switch. This would entail setting a new boolean preference for all of the extension's simpleprefs in the format "services.sync.prefs.sync." + [simpleprefname]. Enabling this feature would set all of those preferences to "true". Disabling would flip them all to false.

I'll try to figure out with Erik and the sync team on how best to do this.

I don't think this blocks making simple prefs stable.