I ran 5 hunters to 70 and had some trouble in UK
If you make sure you have a different pet focused on each different enemy in pulls in 70+ instances or you have the patience and skill (i didnt) to crowd control and take one mob at a time then high end instances are do-able but not plow-able like lower level instances. Getting to 70 is fast as hell. The gap between pets and real tanks become huge from 70 to 80 though.

Note: I had total shit gear