This is the first I've heard about disc scratching by the 360. I looked up that Wikipedia article you mentioned and apparently it isn't limited to the slim version. It's been happening for years.

I never move my consoles with a disc in them, so it's never happened to me.
I think I would have been happy paying the 25 cents extra to avoid the problem. It might have delayed the original launch, but there's little acceptable excuse for this not being fixed in the slim, given how long Microsoft has known of the issue.