My two 4163B drives have burned many dvd's mostly -R and still going strong, you shouldn't have any need to worry dante02004
4163b - better error reading (for bad disc data) / perfect burning of lesser known medias, most of the time. Found this out after buying two tubs of cheap dvd's. Last time i make that mistake
3500ag - faster at writing and reading
4163b - Is let down in every way by having the riplock active. So no reading any dvd media at speed no matter what mode you burn it in. I'm sure the burning speeds are slower than the3500ag also.
I can't wait for a firmware to do away of the Riplock on this drive, amazed it has not been done already.