Originally Posted by MacCool

Different people see the dots on red-dot-sights differently. Some people see a lot of distortion, fuzziness, comma-shape, etc in the dot no matter the magnification or brightness and that variability between people is usually due to amount of astigmatism that their eye's cornea imposes. Some people have so much astigmatism that red-dot-sights simply aren't useable for them, in which case they're better off with a second-focal-plane zoom/magnified optic.

Astigmatism is usually well-corrected with accurately ground prescription lenses. Hint: your 1-hour budget lens grinder at your local mall is usually not the best place to get accurately-ground corrective lenses.

I have a G33 magnifier and a G23 magnifier mounted behind various optics, including my 4 MOA T-1, various Eotechs, and a couple of 2 MOA Aimpoint PROs. The magnifiers work great for me. I flip them down for any shooting 25 yards and farther. The G33 is definitely a significant improvement over the G23.