Just got a late 2013 (2.4ghz, 4gb, 128ssd) retina MacBook pro (my first Mac notebook), came with Mavericks. Should I stick with it, or update to Yosemite? My concerns are the following: 1. Battery life: Does Yosemite take a toll on it in some way? Mavericks boosted all the MacBooks, I don't want to see it going in the other direction. 2. Stability of UI: overall Mavericks is pretty fluid, there's only the occasional stutters in Safari or whatnot - are people encountering more UI stutters on Yosemite? 3. Speed: any performance differences (launching apps, loading things, actual processes) between Mavericks and Yosemite? Just trying to see what the consensus is at this point, or whether people are waiting for Yosemite bugs to be worked out. Thanks!