This is not media, this is 109 new IDE interface. Many people experince the same, no matter what you set for UDMA, what cable you use, etc.
The problem is only related to DVDR discs, DVD-ROM reads up to 16X. Those discs that slow down or even fail to read in the 109, rip up to 16X in my NEC 3520...
This problem has several different threads in this forum under various names.
Personally I couldn't find any reason why it behaves like this with one hardware configuration and why not with others. For example my config worked and works fine with 8-10 different types of burners, only this 109 drives me crazy.