You do realize that deathgrip won't pull just one guy from your 5 man, right? There are going to be 823,234,123,532,234,123,643.883333 death knights rolled on the first day of expansion. For the next year, all 5 of your guys will be pulled at once.

The good news is that the type of people who absolutely must have a death knight will likely pull your entire group into the same place, so it's a push.