With my Pioneer 1015, it hit the overall speaker levels pretty much dead on when I used the auto set-up. What I use my SPL meter for anymore is measuring the output levels over frequency (when I run test tones). I did that to help dial in my subwoofer.
Like ninja12 said, it can't hurt. However, if your Pioneer did as good of a job as mine did, and you're not trying to fine tune your system over frequency, you're probably just fine as is.