I have dan's sight on my gun.. well the prototype anyway.
Finally got to hanjdle an M&P with a warren on it, and I'm going to give it a try. The U notch is interesting, and on my 1911, I definitely preferred pyramid style sights to sqquare blades. But the real deciding factors were that the warren is not sharp and that the rear was not serrated and not canted forward. Dan's was gouging up my right arm arm and left hand regularly, and the canted forward rear plane got a lot of light onto the serrations, which meant you REALLY see them and they were exposed to more bumps and bangs. So you wind up with bent serrations and sight black just doesn't completley cover them up to be undistracting.