Getting them moved is most likely a losing battle, but if you are very dilligent you may be able to pull it off. I wouldn't go through the effort if you don't need the miles for elite status.

One thing noted above is that you have to get them to remove the DL number from your PNR. If you have both numbers the DL one will still show and be the credited account. I've had this happen before (but noticed before boarding and got it resolved).

As for upgrades, DL will not upgrade a NW elite based solely on status.

S.