I got a 21.5 Fusion Drive, 16 GB, 2.7 Ghz on the way. I know the 21.5 have a 5400 RPM HD standard while the 27 inch have 7200 RPM HD standard. However, if I have the fusion drive on my 21.5 will I even notice the difference between 5400 vs 7200 RPM? Won't the SSD be responsible for the most "common" files on the Hard Drive? Basically, outside of major data transfers, will the average fusion drive user notice a difference between the Hard Drive in the 21.5 vs the 27?