I had quite bad results with my LiteOn 20A1S even with Verbatim media @ 2.4x. My new Samsung burner produces good results with 8x Verbatim media at 8x and great results at 4x, but burning them @ 2.4x is not possible.
http://club.cdfreaks.com/2117212-post94.html
MKM 003 @ 4x: Average PI Errors are ~ 1; Average PI Failures are 0.00. (Results depend of the drive, of course.)
The quality of the fake 8x Ricoh media is good enough to burn the first layer @ 8x, but the second layer needs 4x for good results. If this would be possible, this would speed up a lot without relevant loss of quality.