I notice DVD writers tend to have louder motors than cd writers, etc.
They also have different characteristics.. some like to spindown fairly quickly, others like to keep on running at speed for a bit first.
Some motors pulsate, others are steady, etc.
I've heard that the retail Pioneer DVR-A09 is the quietest DVD writer, but it's very expensive and the OEM -109 version does not have all of the quiet tech the retail one does.
Other than the noise issue being of annoyance, I feel it can also affect quality.. if you have a large powerful motor shaking around generating whine and vibrations, it can probably cause the laser to have a harder time of it being precise.