Glazers have been around for about 30 years or so, and can be a devastating SD round. Trouble is, there is no way to know what your self defense needs will be ahead of time. If you have to shoot through car glass, walls, doors, heavy clothing, etc., Glazers won't work well. And no, Air Marshals don't carry them. That's sales hype.
I've never heard of a police department which has officers carry staggered loads for the same reason. If your adversary is behind a barrier, your first 3 rounds or so are wasted, so you effectively get into the fight late and under armed. I've been a firearms instructor, military and police, for over 30 years. I've never heard of a special police ammo that goes through auto glass at a certain angle. What is taught is, glass, especially windshields, will defelct bullets and your point of aim will be very different than your point of impact. You can not shoot through glass with any degree of accuracy.
Stick with major manufacturer SD rounds and you will be better served.
(http://i204.photobucket.com/albums/bb294/pioneer461/police.png)