Long time lurker and reader of the forums! I have a late 2012 13' rMBP and was considering upgrading to the most recent version of the 13' rMBP and was wondering what kind of jump in performance I could expect. I'm a pretty light user; I would be using it for web browsing, keynote presentations, and light photo editing in photoshop. Being that I have the base model now and was also probably going to get the base 2015 model as well, I'm not sure there would a whole lot of noticeable increase in performance for what I do. Worth it to upgrade?