Currently on 3 and haven't had much trouble. Getting fantastic battery life on my 2014 Air, around 10-14 hours. Only minor issue is Safari occasionally freaking out on me. I ignored the PB4 since I heard a lot of trouble with it, but 5 seems to be solid. However, at this point the actual release seems imminent. Is it worth going through the trouble of going from 3>4>5 tonight?