And what if I -only- use Sandbox +? Nothing will happen unless I use a command like the Superpowers command, right?Yes, it should be playable, but some things may be slightly glitchy. If you do coop with vanilla users, I would suggest not selecting a couple of mods in GoS:
* Extra clothing and makeup colors will make parts of your character look invisible to the vanilla player if you use any of them
* GPO (Gang Plus One) could cause issues if you use any of the new gang types