According to sources, Plextor will support at middle of March DVD-R DL format... with the fastest available speed of 6X (not so sure about either P-CAV/Z-CLV). According to already posted specs, the DVD-R DL writing was expected at 4X, but as it seems Plextor boosted the writing speed to 6X. The new firmware expected to arrive middle of March 2005. Summing up, the final specs of PX-716A would be:

16X DVD±R
6X DVD±R DL
8X DVD+RW
4X DVD-RW

DVD+R DL writing also will be boosted to 6X with the upcoming 1.04 firmware and 8X +RW would be added too. Congrats at Plextor for the increased writing speeds, as soon as the firmware released, CDRInfo will add the test results to the upcoming PX-716A review...

Update:

After our initial post, new, this time, official information posted about the upcoming firmware release: "...Free of charge, Plextor offers for its award winning Dual Layer drive, the PX-716 series, a firmware upgrade to support higher writing speeds. By this upgrade Plextor offers its customers protection on their investment for the future. They are the first to introduce to the market 6x DVD+R DL and 6x DVD-R DL writing. Besides an increase of the Double/Dual layer speeds, 8x writing on DVD+RW media is supported, and additional support for 16x writing on DVD +/-R is added.

Middle of January, firmware 1.04 will be released to support:
* 2x(CLV) writing on DVD-R DL media
* 6x(CLV) writing on DVD+R DL media
* 8x writing on DVD+RW media
* Support additional 16x media

Beginning of March, firmware 1.05 will be released to support:
* 6x(CLV) writing on DVD-R DL media