I posted this in the Final Fantasy problem thread, but thought others might be interested in this topic, so I made a new thread for it.
I buy 12x - 16x media.... I ALWAYS burn at 8x (which burns at 6x for the first 10% and 8x at the last 90%). I never had one issue with PS2 backups, Wii backups, GC backups, or DVD movies on any of my players.
This is using many different brands of media also. Note that when you burn at 16x, it really only gets to 16x speed at the very last minute or so of burning. To see the actual burning speed, use IMGBURN and watch the Write Rate -- you can see when it switches speeds. I found that burning at 8x is only about 1-2 minutes slower than burning at 16x (not 1/2 speed like you would think).
Another hint -- overall I read and think myself that "Taiyo Yuden" brand is the best DVDs over any others. They are more expensive (abt 60 cent for inkjet printable, last time I bought them -- the price is always dropping), but not too bad. Also, ALWAYS verify your burn! Nero and Imgburn both will do this automatically. It takes a few more minutes but it's worth it! Not that I ever get verify errors with Taiyo Yuden.... Remember that a blank disc CAN be scratched, and if you don't verify you are screwed! Also, I look at each disc when I go to burn one under a very bright desklamp, you will see dust / debris that you never would have known was there. I gently wipe the debris off with an eye-glasses cleaning material, then pop it into the burner.
Hope this info helps someone -- regards,