Talked to a guy who mounted some on his 1911 slides. He really liked them. One slide was wearing a 3 min. dot and the other was wearing the 7.5 min. dot. (I believe these are the sizes). He also installed taller front sights so that he could use the Optima as a rear sight, though I don't understand the reasoning behind that.
At around one ounce in weight they didn't affect the handling or operation of his 1911s at all.