Good points, it's true it's only a matter of grams, but the aluminum feels like nothing while with the steel you do feel it. I don't mind, as I have steel for two years, and it looks like I'm going to have Space Black steel this time. If I had ordered the Space Gray with Gray sport band, I might have gone with Space Gray. Or if the Nike Space Gray was available now. But I have Space Black setup with cellular and don't think I want to delete cellular and set it up on another AW. Space Black does look a bit better IMO than the Space Gray, especially with the Red Dot. I think the Red Dot looks a bit better with black. I had a small number of very fine scratches on steel, wasn't worth polishing out, but with Space Black I don't think those very fine scratches would even show up because of the DLC coating on the Space Black.
In a way, I think the Ion-X glass vs sapphire is a tie. The Ion-X display is a bit more clear to look at, but the sapphire is more scratch proof. Sapphire most likely scratches at Mohs 8, while Ion-X glass scratches at Mohs 6. I don't know if Mohs 8 vs Mohs 6 is a big difference or not, in real life. Some have posted they were really careful and were shocked to discover a scratch on Ion-X.