To be honest all the time you can buy another copy of the game and create a new character you are effectively creating a second character slot. The only advantage to this current method is that FD will get double the money from that user. This method would still allow me to explore with one character and stay in the bubble with the other. So I don't get the argument against multiple slots at all as FD currently don't stop multiple account ownership. So my vote is Multiple character slots as the game mechanics already allows you to play more than one CMDR.