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Apple expert - if you get the chance, maybe you could time and/or video a couple iMovie renders running on each, say a simple slideshow of 30-40 pics with music rendered in HD?
 
Why waste money even if you can afford it? I can afford to light hundred dollar bills on fire, but I'm not going to do that anytime soon.

Obviously you can afford it because your driving back and forth to the apple store to avoid buyers remorse.
 
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