Skwab, I can do the same, at the range. I've owned Glocks for years and have alternated shooting them at the range with my other guns. And yes, I can shoot the Glocks just fine in that senario. But, in a defensive situation, you probably won't ever see your sights.
There isn't that much difference, but it is enough to throw off point shooting. Try it. Go to a range where they let you do draw fire, and close your eyes with your gun in a holster, draw and fire from the hip with a Glock and most any other brand gun. You will see what I'm talking about. I did this test with 4 guys and each of us had a spread of 6-8" up to well over a foot at 5yds. Just try it dry fire and you should see the difference in muzzle height.