Would it be possible that another reason that the 52246S does better than the 40125S because also the 52246S is a better reader?
No question that it is both a better reader and a better writer than any of the "5" series drives.
i dont understand the logic behind 8x read
The reason for setting the read speed in testing tools is that they do not allow the drive to slow and re-read difficult sectors, at least not inthe same way that the drive would normally do inthe "real" world. This is a way of eliminating a variable in the testing process. CDSpead allows the drive to do it's normal thing and slow-re-read, slow even more, etc. You can make a good argument for either approach in every day media checking. Personally, I look for a max speed read with no C2 and low C1. Another reason for 8x reading is to better scan a disc that fails at max speed.