Thanks for the information. The only problem I've been running into with Steam is that when I use the Sandboxed copy to play certain games, it constantly gives me popup warnings about files being saved outside the Sandboxed area and asks permission to move them. For now, I'm just using Sandboxie for trading and helping my Dungeon Defenders group while I play Witcher 3 or something else on my main account. So far this seems to be working without having to make a copy of the SteamApps folder, but only time will tell if something major screws up.