I have dark grey in a pair of plaintiff squared and like them a lot. Im not big on non-iridium lenses but dark grey is dark enough that you can't really see my eyes through them and work pretty good in bright light. As far as aviator styles go, these are perfect for my poished gold frames, iridium would be a touch too much I think.
I believe dark grey is a bit darker or has a lower transmission than warm grey, if I worded that correctly. Warm grey is actually a fairly pleasant lens to use as well.
I like the slight brownish tint to the warm grey. I have also tried the grey polarized, but you could see my eyes too easily through them. Not a big fan of the black iridium polarized cause they look too shiny. If only there was a warm grey polarized...
I have 'dark grey' in a pair of oil drums. They are not so great as the clarity is poor in shadows. They are find in very bright direct sunlight, yet, in those conditions, black iridium would probably elminate glare better. I have yet to try the warm grey, but like that it might have a hint of rose.