I'm not sure that this answers your specific question, but since I upgraded my internal from a 5400 to a 7200, I feel like boot and copy times have improved proportionally. (Sorry, no real benchmarking.)

Edit: Your new iMac is going to have USB3, so I don't think you've got anything to worry about; you may be able to go still faster, but you'll already be going plenty much faster than now under any circumstances.

Last edited by artie505; 02/03/15 11:18 PM.
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