I am planning to upgrade my 3x 1TB Western Digital Caviar Black drives to some 3TB drives. My current drives are 7200rpm, but I would consider buying 5400rpm drives if they would be suitable for Aperture...so here is my question: I store my Aperture library on a 1TB 7200rpm drive currently. If I replaced this drive with a 5400rpm drive, how much of a difference would I be able to notice when working on pictures? My RAW images are generally 20-30mb each, and I use brushes in Aperture extensively. Currently I notice some sluggishness when using Brushes but I'm not sure if that's due to the hard drive or my overall system. FYI, I have a 2010 Mac Pro 3.33ghz 6 Core with 12gb ram, and OSX and my Library folder reside on an SSD Thanks!