staingate is depend on user habit actually,
dont close your screen after using macbook, please wait a moment and make sure heat from topcase not damage your retina screen.
from my experience, you can check spaingate from user spec, they should speak at all, like deadpixel, spaingate, whitespot, etc.
but if you can find mid 2014 will be better, this version have boost speed processor start 2.8ghz (late 2013 maybe start 2.0/2.2ghz).