The space grey looks absolutely stunning. Images really don't do it justice. As long as you're careful you shouldn't get any scratches on it. If you do happen to get a scratch while being careful, I believe the silver would be damaged just as badly.
I think the argument is that if you have a silver and a SG both with the same exact scratch the SG's scratch will be more noticeable than the scratch on the silver and you'll see the silver underneath since there is more of a contrast so the scratch will be more visible on the SG