:iagree: That about sums it up.
PIE/PIF scanning does NOT show possible unreadable blocks, as user data is not read during a PIE/PIF scan. The opposite is also true: you can see POF errors in a Benq scan with a disc that is still readable.
DrageMester and myself, as well as other posters, have mentioned cases of good-looking scans of discs that failed a TRT (or a scan disc "reading test") in at least one drive. So these cases, while scarse, should remind everyone that PIE/PIF scanning, while being unvaluable for given uses (comparing burns, checking for degradation), are not the "one-fits-all" testing that many users have come to think it is.
If one really wants to be 100% sure of the integrity of one's data, one needs some sort of real-world reading test, like a transfer rate test.
The other lesson is the same old one, which is: the behaviour of a disc in a given drive is not predictive of the behaviour of the same disc in another drive.
As a sidenote, I kinda concur to the idea that Benq drives are peculiar readers, to say the least. Though I think they're fantastic burners.