I find the Fat Boy to be extremely sensitive to angle, much more so than my other DE`s. If the angle is a little too steep, and even a tiny bit of pressure is used, irritation is sure to follow.

Setting 5, when used correctly, is actually fairly mild, much more so than setting 9 lol. What I usually do is (what I call) the "5-3-2" technique: 5 for WTG, 3 for XTG and 2 for ATG/touch-ups. I've found this approach to work very well.