They DO make a difference! Take a look at this. On the left is a new Colt slide stop for a M1911. On the right is the same from Wilson Combat.
Click to enbiggen!
Take a look at the blue lines. The Wilson and STI were both hitting the lower resulting in scratching the bluing. I don't know if this little ridge results in not doing that, but I had no such issues before.
Take a look at the green lines and the red ones. Remember when I had to file the STI stop for class? The Colt stop seems to have additional contours to facilitate loading of the cartridge with no mechanical interference from the stop.
So now installed, off to the range for testing! I believe that I will have no problems!