Well I don't think there's too much worry about the furloughee on the street wanting to be in class, since he will have already bypassed. I do agree that accepting and then resigning at the latest possible date if you don't decide to go back would be best, though not really the most upstanding thing to do. Personally I'll probably accept and then plan on a definite notification to them 2 weeks out if I decide against going back, just as if I was resigning from an active position.