I'm looking at getting a mid-2015 or 2016+ MBP 15" to use in clamshell mode as a permanent desktop. It will rarely ever be used as a laptop. I will be using it for normal tasks, parallels, and CAD work. There is about a 500.00 difference between the models and other than the convenience of the TB3 port for using a dock. Is there a reason to go with the 2016+ over the mid-2015?