I was under the impression that the PI counts in BenQ quality scans included the PIF counts as well.
Here is a partial scan of a DVD+RW that contradicts this. The PIF levels are almost double the PI rate- so they cannot be included in the PI counts. (I did a partial scan because the counts rise at the end and obfuscate this information).
I checked older versions of CD Speed back to 3.50 and they all showed this behaviour.
Interestingly, the advanced quality scan differs: here the PIE values are higher than PIF.