I bought a LiteOn 811s two months ago and haven't changed the firmware (FSOE).
The first 30 DVDs took some 20 minutes each to copy to the harddrive (with Fairuse).
Also, the first 15 data DVDs I burned, took some 15+15 minutes to burn+validate (Nero Express 6 at 4x).
However, two weeks ago, all these times doubled!
I back up the same quality of DVDs (in terms of scratches and fingerprints).
I write to the same media type (Ritek-R G04 and TDK/MXL+R, all 4x).