Sir William,
One of the guys I work with has them on a Glock 19. At first glance, they looked awful high and big on the gun, but turned out to be an optical illusion. The colors are BRIGHT and the contrast is good.
It took me 15 or 20 rounds to get the hang of it, but sight/target aquisiton seem quicker. Wasn't on a timer so that is a subjective statement. Accuracy was good for me out to 15 yds on IDPA targets, but I wouldn't shoot bulleye with them.
The best comparison I can make is that they are an improved guttersnipe type sight. I wouldn't replace my Trijicons on my carry guns, but am considering a set on an IDPA gun.