I've got two standalones (less than 2 years old) that play the DVD-R DL just fine..
But I had a hard time getting them to burn (Ritek P01). I was only able to get these to burn decent on an NEC 3550A and Optiarc 7170A, I was impressed with the scans, very comparable to many of my MKM 001 burns.
However my Benq was very sporadic, and would error out before completion nearly 50% of the time. My Liteons and LGs created complete coasters on every attempt.
Because of burner compatibility, it's just not a good gamble when it comes to ~2$ a peice discs.