I love my Retina. I haven't noticed problems with scrolling, I have my resolution set higher than 'Best for Retina'.

I upgraded the SSD with ease, pops in an out once you remove the pentile screws to open it up. It's easy to do and your point about "None of the components can be upgraded" is incorrect. I don't believe anything else can so it is limited but this was enough for me.

Source for one way to upgrade: http://twit.tv/show/know-how/10