Certainly not to correct you at all, the cleats are very new, my LBS guy showed them to me a few weeks ago when I stopped in and got my replacement 6° cleats. I hadn't heard about them either. I like the 6° models and the SPD-SL 105, PD-5700, pedals a lot, I had the PD 540 line and when they wore out I moved up a level. I use the slackest setting for the tension, no pull out problems at all. I cannot rationalize the 4° cleat myself, the difference between a 6° and a 4° is very slight, I am not sensitive enough in my feet to feel that one.