Is there any worthwhile difference between the first gen and second gen rMBPs, aside from clock speed? Second gen is more expensive. I heard that it might have some newer parts, but I haven't heard of any of those parts actually affecting anything. Image retention, high temps occur on both models. Has anyone actually noticed a difference? Also, how much hotter is a 2.6 vs a 2.3/4? I might play some games, some cpu intensive...I want to avoid throttling if possible..