I have flown 15 times in the last 9 months on LH and OS K, L and S fares. Each time, I use a TK*G or A3*G card to get FFP service benefits and then retroclaim mileage on M&M 14 days later - it works every time. With T class, it is best to use TK as they credit 25% mileage and you get nothing on A3.