Is the dark grey lens similar to the black...
Is the dark grey lens similar to the black iridium in high light conditions?
As far as looks go, the black iridium appears chrome-like, and the grey appears as the color black.
The grey and black only let in 10% and 18% of the light respectively, so they are for sure ideal for high light conditions. I have used both and have the dark grey lens right now. They actually have a blue-ish tint to them from the inside (when you first put them on). As soon as the sun goes away you can't see much at all. With the black lens, the have a slightly amber colored tint from the inside and are a little more versatile for variable light conditions.
For bright conditions id deff recommend the dark grey.