Guy I work with has 2015 SLT HD and put 3" leveling kit almost after he bought it and loves it (New upper A-Arms and Keys) so I'm debating that route. I just rolled 23K and I'll have owned 3years next month.A friend of mine is the GM at one of the GMC stores now and I was asking why they don't offer that color anymore and he said it was one of the worse selling colors. I told him he is crazy. I still get compliments to this day on my truck and I haven't done anything to it since I drove it off the showroom floor. It's got 55k miles on it now so been trying to decide what to do about a 6" lift and tires or leaving it stock.
Be very careful with the leveling kit. The dealership put one in my truck and had to go back and adjust because the A-arms were hitting the frame when the shocks compressed. A buddy of mine has your exact truck, lives in Utah so does a lot of off-road travel, just different color and he put a leveling kit in it and cracked the frame. He just traded it in on a Ford 350 Lariat.