I just did a burn and it almost immediately reached 6x and even though it was supposedly limited by ImgBurn it still maxed at 7 point something. Seems like a good sweet spot.
My Taiyo Yuden DVD5 I believe can hit 12x but I'm pretty sure I've never gone over 8x. I've had discs that I've burned BELOW rated speed and having crap quality to show for it but better quality at it's max speed.
I tend to trust rated speed. I was just curious what results people have seen.
That said, I know it isn't RELIABLE, but is there some software that will actually allow Pioneer drives to do a quality scan? It should be informative at least for a comparative basis.