With the finger scan I understand that the hand stamp is no longer needed. Just put you ticket through the card reader and place your fingers in the scanner.
If you see a CM at the exit putting hand stamps on people by all means get one, if no one has a stamp pad and rubber stamp don't worry about it. Just be sure you don't accidentally swap tickets between people in your party as the WDW computer ties your finger scan to your ticket and if you should somehow switch tickets the computer will not recognize you as the legal ticket holder.