And how long do you think that DL/NW will still participate with YX on redeeming miles? That is going to end sometime soon IMHO. Then what, you will be able to redeem them on YX or YX? Sometimes it is better not to put all of your eggs in one basket. Always have a back up plan. Once you hit a milestone on one airline, start putting the miles on another. Then you at least have a choice.