I currently own the top of the line late 2013 rMBP 15 inch with core i7, 16gb ram and 512ssd. I don't do any heavy tasks like gaming or video editing on it. I recently returned my iPad pro as it was way to much for what it brings to the table. My MBP is mostly a stationary desktop replacement that powers a 27 inch 4k display but i hate taking it anywhere because of its size and weight and was looking for something more portable that could replace the iPad pro and the MBP for day to day use. Will the Retina Macbook will be able to accomplish what i need and be able to power the 4k external monitor at least at 30z? Also, I'd be getting the Macbook at a steep discount of $900 shipped.