Absolutely, positively YES. It's not needed on every card, but there is no better way to get your image stamped exactly where you want it. Even when using clear polymer stamps, I still use the stamp-a-ma-jig to get my sentiment placement dead on.
Although I don't own the SU branded one - I have one from Michael's. Addicted to the 40% off, I am.
~~Cheryl, with a "C"