I'm down to picking between an i7 or an i5 top tier iMac. The difference is $200. Should i use that $200 towards increasing my Memory (additional 16 for a total of 24) or get the i7 instead?? the iMac is going to replacing a 2011 i7 iMac with 32gb RAM. will be mainly used for photography specifically stitching 80MB files and HDR processing. With the occasional 4K editing from iphone/GoPro. your thoughts are much appreciated.. thanks!