I did dig into this

I got two agents to say this can be done for us$120 (consistent with http://www.flyertalk.com/forum/catha...l#post26093391) , with a possible reduction to us$100 or even us$25 for CX <--> KA, but generally us$120 if a non-CX/Ka partner is involved (I also had one agent saying changing to/from a partner is not possible under any circumstances)