This man is absolutely correct. It is the ONE to have if you are to have just one. BTW, my opthamologist showed me the distortion level difference in polymer vs. glass versions using his equipment. Though "good plastic" is better than bad plastic, it still doesn't compare to optical quality glass, which 580G is. 580G is one of the thinnest/lightest for glass, doesn't bother me a bit.
I now also have the blue mirror for offshore & super bright days, but I made do with a single pair for years. I added the blue mirror pair because they are darker and I'm super glare sensitive. The spec says 10% transmission vs. 12% (green) but something makes the difference to the eye very noticeable - light intensity gets stomped on significantly with blue mirror in my experience.