no the heatsink on the arctic is so rough and its not flat because i put my ruler over it and there is a gap in the middle, thats why i want to lap that thing, i get really bad temps it gets so annoying. so going beyond 600 grit is just for show? or does it improve thermal interface?
Since your HS is concave then once you get it flat I imagine your temps will improve! Just remember that when we talk about improving don't be surprised if it's only a 5C difference or even a 1C difference, every little bit helps.