I use my AC*G for perks and credit to SK. If you get a printed BP with your *G status you can change the FF program in the SK app before you board. Then use the paper boarding pass for lounge access and zone A boarding. The only time this caused a problem was when I had checked luggage that was free with *G and would have incurred a cost without. The BP wouldn't open the scanner and the GA wanted to charge me. I showed my AC*G card and was able to board without paying baggage fees after some effort from the GA.