I had been thinking about it ever since reading my GS500F manual when I first got my bike. I never thought it would make much difference so I never bothered. While waiting for a mate to come around today to go for a ride, I thought I'll have a play. I moved it from a 3 to a 6 (I weigh 92kg and do mostly twisty riding). Oh my God, the twisties felt great and the bike felt much more planted. I'd recommend everyone at least have a play.