Got a 2012 with a Fusion, and gotta say, I cannot tell the difference from a full SSD in 95% of ordinary use. Booting, application opening, movies, are all super fast. The remaining 5% of use, I can merely hear the drive work, still doesn't seem to influence the SSD-like speed. To me this is like cache. If power users had their way, all RAM (including GPU cache, CPU cache, video RAM, system RAM, regular data storage) would be L1 cache RAM. It would be astronomically expensive, but hey it's fast 100% of the time! No one needs all storage to be L1 cache. Assuming HD and SSD keep their trajectory in terms of GB/$, and correcting for larger files in the future, does anyone really need more than 1/4 of total HD capacity to be SSD?