Eakins, The dark gray is hard anodizing and has nothing at all to do with looks, aluminum is a soft material and a poor wear surface for the Teflon piston band to run on. What happens is a little higher friction to start, then the aluminum starts to wear and makes fine particulates enter the oil making a more abrasive slurry, causing more wear and so on. The cast aluminum body of these lower priced shocks are the worst offenders. By putting this special coating on the body, there is a 0.002" "skin" that is hard as glass and this is a very good surface with less friction and excellent wear resistance. The oil stays cleaner and the shock lasts better and works better too. the coating makes the body first class for building a new shock on. If the original body is scored or a little worn, we use a special honing process to bring the bore back into a good condition (a little like redoing a cylinder). I am not at all into bling, it's all function
I generally talk to each of my customers about the shock set up and yes these things are considered. I am about 215 lbs and used the stock spring with the gold valve setup and felt it was excellent. I really think the stronger spring is needed only over the 220 lb mark. Check your sag now, look for the 3.5-4" of sag (about 30% of your travel) and see how much unloaded sag you have. If the unloaded sag is a small value (say 1/4 inch) then your spring is too soft, if on the other hand it is a big value (like 2 inches) your spring is to stiff.
I did the Gold Valve with the RaceTech recommended settings and it was good but could be a little stiff when it hit the secondary stack (I actually thought it was bottoming before I ran our shock travel data recorder on it. I could not bottom it, even jumping (OK small jumps but jumps). If I were setting up another, I would use a softer secondary compression stack.