Yes, this way you are ablecan move on the next difficulty without beating all the quests. You just need to gobeat the final boss to a newunlock the next difficulty. Beware Beware that certain difficulties have a level cap, for instance, you can't enter inferno unless you are level 60.
I did this trick with a buddy of mine. He got me past the last boss, so I could train on the higher level monsters in the next difficulty.