I'd just have to say that qualifying for Gold is quite difficult, but keeping it is not too hard (just similar to most airlines). Like you said, the benefits for Gold is nearly nothing if one always fly in C, or I should say you get some extra luggage (not sure if you need it)? For ones who fly in Y, you get some extra luggage plus a lounge access, so a little better.

I don't know if typing Chinese is allowed or not, but making it simply a chat room is probably not a good idea.