I would say lower PIF is better than low PIE, since ppl in other threads have said that PIF "is more indicative of how good the burn was." I can say that when there is PIF clumping (a PIF block with no separation), it does seem to indicate a poorer burn in my experience. When I rescan my disks (I have a number of RitekG05s from when I didn't know they couldn't be reliable), I rescan sum1/PIF only to see if the errors are the same/within variance/or increasing
I will share this, that's from scans I've seen and burns I've done so this is NOT scientific in any way:
<100 PIF total--truly exceptional
2501+--getting in uncharted territory and probably not good
Again, this is what I use to measure my burns by, although many of the 'average' and lower burns are still playable, but I'm suspicious of those higher PIF totals, so I will be rescanning those at 2 mo intervals to see how they hold up.