That new fee to transfer miles from one account to another (as of Aug 1, 2009) is USD180 for the first 10000 miles, and USD150 for every 5000 miles thereafter. If you think about it, the fee doesn't really make any sense since CX does not limit the amount of transfers you can do...

But anyway, no matter how much it costs, it's still too high to justify, as KO2546 said.

That being said, if your wife usually does not travel enough annually to sustain a MPC membership (which i guess is what you were trying to say?), just go with AM. As mentioned, you won't get any club miles from her, and if you want her miles, you'll have to do it through transfers (as mentioned above)