I recently purchased a refurbished Panasonic DVD Recorder.  When I was trying to make up my mind about the unit, I googled the different models and found excellent reviews on the internet for the model which I purchased.  The eBay seller was absolutely honest and accurate in his description of the unit.  I left him GOOD Feedback.
However, I soon discovered that the particular model Recorder was about 3 models old.  It worked just fine with the Panasonic DVD-Ram disk which was included with the unit.  But, the current 16x and 8x DVDs would NOT work in the unit.  There are numerous good deals on quantities of 8x and 16x DVD media, but the 2x and 4x seem to only be available in -RW which are much more expensive.  If you plan to make many copies, you might discover that a newer more expensive DVD Recorder is ACTUALLY cheaper, because the media is a lot cheaper!
Nothing in the manual and NO ONE at Panasonic ever told me what speed media I had to use.  I sent the unit back under the warranty, but Panasonic could find nothing wrong with the Recorder.  In the mean time,  I purchased a Samsung DVD Recorder which is a new current model and it works great!  At the retail stores where I bought media, I couldn't even find the Panasonic DVD-Ram disk for sale.  A clerk told me they stopped carrying them because they were so expensive and no one was buying them.