We've tested the Wytron DVD-3000 "on-the-fly", achieving <10mins copy time for a full capacity DVD-R or DVD+R. You can shave about a minute or so off that copy time if the source is a hard drive.
The controller needs to be min. version of v3.03 and we used a Liteon 166 16x DVD-ROM reader along with 9 x Pioneer 107s. The Pioneers need to be flashed to the latest official Pioneer release (or you'll just get 4x write speeds).
Tested media was Ritek 8x dye. Using certain media unknown to the firmware (of the DVD writer) may also drop the max. write speed down regardless of setting the controller to "Max" or otherwise.
Wytron UK will soon have all these support issues under control. Probably in a few months