The website
www.CDFreaks.COM is a great product-reviews site that illustrates problems with the so-called 2.4x burning speed (which has a poor compatibility record with many Players), as well as lengthy discussions on the non-existent DVD Manufacturing Standard.
Since Sony-Phillips forces a royalty payment on every CD disc made, the DVD makers refused to observe any standard and pay no royalty, and every DVD maker has their own manufacturing guidelines for discs.
This means that, from plant to plant, even at the batch level, DVD Blanks can be made differently. Having a brand-name spelled like "Maxell" isn't guarantee that Monday's purchase of Maxell blanks will be the same as next month's purchase.
That's where a DVD Burner's firmware updates come in.
CDFreaks offers the best 'clearinghouse' section on Firmware updates, although I usually revert to the original manufacturer's website, if possible.
But for a company like "Sony" or "Phillips" or "Panasonic", finding the DVD Firmware Website can be tricky.
CDFreak's Burner Reviews are some of the most exhaustive (depressingly so, at times) reviews I've seen, where they'll use 6 or 8 or even 15 different DVD Blanks on a certain burner to get quality tests on both the burner and the disc-blanks.
The short analysis: GOOD LUCK. The best advice they offer is "Burn at slowest 2x or 4x speeds, never use a fractional speed and remember - burning speed is NOT the goal - PLAYING the disc is the goal."