Hey guys, I currently bought the new 2016 rMBP 15" base model. I've been looking at external monitors for my my Mac but a 4k 27-28" cost at least 500 dollars while a 5k monitor cost around 1000 and the lg one costing 1300. But can buy refurbished 2015 iMac around the same price as a 5k monitor. I did hear I can't use the iMac as a external monitor so I was wondering how the iMac will run compared to my new Mac. I was thinking of buying the 2015 iMac with a i5 3.2 quad core and the radeon r9 m390. Would upgrade the fusion drive to a ssd and upgrade to 32gb of ram. Currently I have the base model with the i7 2.6 quad core, radeon 450, and 16 gb of ram. I know I'm doubling my ram but how does the cpu and gpu compare between the two. Will be using adobe stuff (mainly illustrator and indesign) and architect programs (auto cad, 3ds max, and revit) Also, does changing the hard drive and ram void AppleCare?