And I just found this out about the status of DVD-'DL-R'
Checking out the firmware update to the Plextor PX-716 (new 16x DVD+-R, '6x' DVD+R DL drive)
which currently sells for $85-95 USD...
"Date posted: January 24, 2005
Added support for 2x DVD-R DL (dual layer) media
Add support for 6x writing on DVD+R DL (double layer) media"
And they say firmware upgrade to 6x DVD-R DL in march.
So from what I have found out, the 2rd Generation of DL drives that have 4x +R DL burning, will probally
for the most part be firmware upgradable to -DL. Currently only Plextor has support for this.