Burning too slow is often just as bad as burning too fast.
It's possible this may apply to the latest / newest DVD Burners on the market but not necessarily to the Burners that have been on the market for some time now like the Pioneer 103 for example. I own three separate burners, all Pionneer (103, 107, and 110U). The newest S-Drive I own is a Pioneer 110U in an ext. FW Enclosure. Originally my G4 733 came with a Pioneer 103. It still works but it now lives in an older G4 PM as a backup ... Still works great (at SLOWER BURN SPEEDS)!
But slower is better on this particular early model /S-Drive. And the same applies to the Pioneer 107. However, it does not apply to the latest Pioneer burners like the 110U, 111, nor the 112.
As pointed out in the above article you mentioned media can and often does contribute /influence the actual write speed that the drive will default to when burning a DVD. Very good article btw and thanx for bringing it to our attention.
Contrary to what is written in the above article though .... "slower is better" provided your burner is also an earlier model (and perhaps not so if you have the latest/ newer burner/s).