I am CO Gold and have had mixed experiences with the AF CSRs. I'm flying BOS-CDG-DXB in May and had some trouble getting my elite status to show up in the reservation. I was trying to book seats on the 744 upper deck. The first CSR I spoke to said, "I don't know what to tell you (i.e. the ultimate passive aggressive response) It's not here. You'll just have to show your card at the airport". They seemed in a hurry to get me off the phone.
The second CSR I spoke to was actually very helpful, and tried removing my OnePass number and putting it back, which did the trick. Then she offered to book my seats for me on the phone, and recommended which rows I might want to choose.
I think it's the same with any airline- it all depends on the person you get. I've had some truly cranky CSRs and some incredibly helpful and accommodating ones with CO.