The comes up about every 6 months, you can do a search on it. I have never seen a good review of these rudders. If I remember right:
the stocks are not stiff enough
the blades are not well balanced
florida people saying they want to sail with blades half down

I think one time a dotan salesman came on this board to defend the rudder, so maybe they did a redesign. I personally would not use them on my boat after what I read on here.