If your main priority is comfort, 21’s were the wrong choice of wheel I’m afraid! I’ll be going for 19” turbo’s on my S for reasons of price, handling & comfort! Curb damage is also a concern to me as, however hard I try, I know I will eventually hear that grinding noise and my heart will sink into my boots
I can’t bring myself to pay £3k for a set of wheels I know will eventually get at least some damage, but I will pay a grand for 19s as 18s just look too weedy on a Macan! Personally I also think 21s look ‘silly big’ but each to their own. I’d always go 19 or 20.