I have a Pioneer 108 burner and at this point use the TY's 4X - media and burn at a 4X speed. Have had only one bad burn in over 200 discs and can't blame disc because I had some stuff running in the background. The 4X speed has eliminated many pixeling problems, freezing etc when I was using other media than the TY's and burning at 8X or maximum burn setting. In other words the TY's combined with 4X burn speed has been a good combination for me. Am at the point of ordering more media and want to know if the 8X or even the 16X burning at a 4X speed would give me a better quality burn and end result.The 4X's are cheaper but they will end and if I am better off using 8X or 16X would like to know. Saving a few minutes increasing burn speed isn't a important factor for me at this point - just good quality with no problems during playback. I also like saving a few pennies per disc but want quality. To me nothing is more frustrating than popping a disc in a player and having to play with it to watch it.
There won't be much if any quality difference. Your using the best media available for the job already, I'd recommend you just keep the burn speed down to 4x to give you the best and most reliable quality result.
The thing to do here would be to test the 8x or 16X media with your burner at a range of burn speeds. I've tested TYG02 at 4x and 8x using my Benq 1620 and cannot see any differences in KProbe or Nero quality scans.
The one area you might want to look at carefully is jitter, a recent investigation by the US national standards institute into CDR/DVDR longevity cites this as the key indicator of burn quality.
It may be that the higher speed capable media will allow for sharper pit/land definition when burned at lower than rated speed, which should improve jitter figures. I must say that this was not case in the TY test I tried, but there may be burner/firmware issues that complicate matters.
