If you want easy adjutability then yes its worth it. I used the FRPP one which is 9 way adjustable. And yes, advancing the cam will bring the powerband down, retarding it will move it up.
If you are running a stock cam, I wouldnt advance it though. You should have plenty of low end unless you have other parts that are mismatched.
A lot of people retard the stock cam to bump of the powerband and get a little more RPM out of it.