I am about to buy a 21.5" iMac for audio production. When I compared different models I realised that some older models actually seem to be more powerful than the latest one. Right now I am specifically looking at the 2012 and 2013 i7 3.1 GHz Quad. They have significantly higher Geekbench 2 scores than the latest i5 2.8 GHz Quad. Is there any reason why I should buy a new one rather than one of those two, given that I get an older model for half the price? Is there any difference between the two models mentioned in terms of configurability? Can I have the fusion drive replaced should it ever brake? And ... is there another used model I should take a look at?