Contrary to what most people will tell you, I think that most people are mislead when it comes to hang 5's. They get told that you balance mostly with the foot off the scooter, when in reality, most of the balancing motion comes from your foot on the headtube kicking the deck foward (when you're about to go over the bars) and backwards (when your back wheel is about to hit)
The foot that hangs off the scooter pretty much just compensates for whatever your other foot does. The reason why hang 5's are easier than nose manuals is because your centre of gravity is better placed over the front wheel, because both feet are around that area, instead of having your back foot all the way by your dropouts.