The last disc of this cake box I burnt in December 2012 with a Plextor PX-L890SA 1.07 @4x speed.
On the same day I did a quality scan with the same burner @4x.
Today I did a scan with a PX-B950UE. Unfortunately @max speed. But to be sure that it is not caused by the higher speed I did a range test @4x.
As you can see the results are pretty bad.
But the disc is still readable. I burned till now 10 of the 25 discs. One was a test disc. 7 of the other 9 are not readable anymore.
As you can see at this burn it looks so whether the discs are degrading only after burning. I was checking again. I bought the cake box already in 2008 and not 2009.
The transfer rate test looks normal.