I've done some DVD+R DL tests on the PX-716A with media I just got in today, and thought I would post it.
First is some RiData 2.4x DVD+R DL burned at 4x, and took 26:37 minutes to burn. Below is a PlexTools Scan:
Next is some Verbatim 2.4x DVD+R DL burned at 6x, and took 18:11 minutes to burn. A scan of the burn is below:
The PlexTools Scan: