I think every *S card is basically useless outside of the airline that issued it. If you fly a lot of LH group in Europe, FTL is quite valuable IMHO, and easy to obtain.

As for A3*G, yes it is a loophole, but it's there for everybody to "exploit". If not having *G makes you feel inferior, just sign up with the program and get yourself one. There's a lot of potato salad in the SEN Lounge to be had.