English is not my native language too...

So if I misunderstood something, I apologize...

Even if you defending this test, this is not bad at all. I just express my personal opinion, this doesn't mean that I am correct, I just cannot understand how such a quick test can be 100% reliable.
The truth is that if the geometry is too bad, too many gap between the pits/lands, then there will be reading errors since at the specific point the data will be half or not there, in simple words.
I think the more information you have about a disc the easier is to judge its condition. What I want to say is that if you know the PI/PO and such errors, the geometry and the jitter then you can safely say that the disc condition is good or not. The hard thing is when half results reporting good quality and half bad. There, what can we tell?
In my opinion the safest way to judge the playability of a disc is to read it at the highest possible speed, 16X if possible for SL. If the reading is smooth then there are no problems. But if it is not then something is going on. I think this test is the most simple while it the most strict judge. Many times in cdrinfo's reviews we have seen low error in Plextools but the reading is not smooth. There something is going on for sure. But I don't remember a case where the reading is 100% smooth and errors in PLextool extremely high.