we have serious problems with our electric co. The power is always going off. I was well over half of my 6th work unit when our lights went out. When I started back folding, I started it as 'service' that way, when our electic goes out again, I won't lose the unit it's working on. It will start back where it left off. Which proved to be the right decision because my computer cut off the other night. The same night others here lost what they were working on.
All of the versions, even the GUI, will restart where they left off; you don't need to run as a 'service' to get that capability. They all write checkpoint information to the hard drive at certain intervals. For example, if it checkpoints every 30 minutes, after a computer crash you should never lose more than 30 minutes of work once the computer is restarted.