The .legacy file can be used as a backup, safely. (from my learnings and research around the community) I just store a copy after every game play, but that is my voodoo. Also from reading, .backup seems to corrupt quickly and has been written that others can play their hoods longer with it removed from the "Saves" folder. I also tend to save it in my "gameplay" folder on my desktop just in case. I am still using the "Save As" method to hopefully keep my hood.
Hmmm, terrific programming from EA there. .backup files cause problems as opposed as to what they're supposed to do which is actually try to fix a messed up save problem. It's like they knew they were gonna screw up so they made
another save file type for people to figure out what to do with it.