I actually see swirl marks pretty easily on my sting gray. Nowhere near as bad as black though. Silver is a great color for hiding scratches and dirt.Always found silver is the best for scratches. For swirl marks Sting grey should be okay. For scratches, sting grey will probably be middle of the road.
I have recently fallen in love with butter wax by Chemical Guys. I am not a fan of all of their stuff, but for whatever reason Butter wax seems to do a good job on swirl marks and it’s pretty fast to apply and wipe off.