the software have no influence on the scan result, because it's related only on the drive.
Not so sure about that in the case of Pioneer scans.
Pioneer drives don't report PIEs as we know it (number of raws with at least 1 byte in error in 8ECC blocks), but the number of bytes in error in 8ECC raws. Needless to say, int most cases the numbers are higher, sometimes extremely higher.
Considering the huge difference in PIE reported by DVDInfopro and CDSpeed, I think it's possible that DVDInfopro applies some custom algorithm to Pioneer PIE reporting to lower the figures and make it more "comparable" to drives that report PIEs according to ECMA standards.
Anyway, I agree with your point about Pioneer drives not being reliable for scanning. They're too inconsistent and, as mentioned above, they don't report PIEs, but something very different.