The PX-40TSi has never been great at error correction anyway ... if you take the time to search for some older reviews from computer magazines (must be around 1999/2000) you will find this confirmed - error correction qualities were often rated at some 50% when being compared to the "best" drives.
I can also confirm the DAE Quality rating for this drive - my old PX40 (in the meantime replaced by another PX40
) did show the same rating on my DAE Quality test disc - and 8x always seems to be the sweet spot for DAE on scratched CD's.