Hi, My mid-2010 11" MacBook Air just crapped the bed and luckily my brother-in-law had a 2015 Retina MacBook lying around as he switched to a Surface Pro. I was thinking of getting a 2017 MacBook before receiving this 2015 and wanted to know if there is anything significant that I will be missing out on. I believe the 2015 unit is a 1.2GHz dual-core Intel Core M processor with 512gb and 8gb of ram. I'm mostly worried about the difference in the graphic cards and the ability to run 4K displays. Thanks.