i'm sure it's the manscaping!

well my other fins don't really spin out either truth be told. ie. MFC freewave fins.
what i like about these slot fins is that they feel incredibly solid under feet and never let go in the gybes in winds over 25 knots. also if the board does lift and you feel the back end starting to let go they just grip again without any sailor input. whereas a standard fin would see you going sideways.
only comment as the others have said is that they are slow.