I have a late 2008 aluminum macbook and the Memorex +R DL discs are virtually incompatible. Literally I had a 80%-90% failure rate with the Memorex discs with a matshita uj-868 drive. I took my laptop in to apple and they put in a brand new HL-DT-ST DVDRW GS21N dvd drive, then I had a 100% failure rate with the Memorex discs. I tried to burn the same iso 4 times with the memorex discs and it failed each time, I picked up some Verbatim +R DL discs and it worked on the first try.
2 bad 4 U I've had 100% success with Memosux DL on XB360 backups. 2 years+ without a failure. I've heard bad stuff about these, but burning at 2.4x have produced zero coasters and long lasting burns. The games are used all the time and are simply kept in disc sleeves when not in use. Only one lost disc due to XBox scratching it (moved while disc was in it.) Burned a new backup disc from the original and the whole investment paid for itself.
I think it probably just that some dvd burners (both drives used in my Macbook) don't work with Memorex DL +R Discs. When I say they don't work I mean that they don't even finish burning at 2.4x (the burning program spits out the disc and give me an error message) I have had 100% success rate with verbatim DVD +R DL discs at 2.4x. The 10-20% of the memorex discs that did actually burn at 2.4x played fine in the 360 though.
The Memorex are likely to be 8X DL discs manufactured with a different, less expensive but more reliable inverse stack process. A DL drive has to have its firmware adjusted for such discs to be able to write "upside down" on the inner layer. Slower recording speeds do not help in this case. Matsushita drives have not been in the forefront of keeping up with compatibility, and I doubt that they support 8X IS discs. Allegro1 apparently has a drive that does support IS discs, and the discs work extremely well for him. This is another example that appears to be one of differences in quality but is actually a difference in compatibility (and political support behind the scenes).
