These days there are only three scenarios where I see optical drive access occuring
Happens so rarely it should not matter.
2. Watching DVD.
Instead of letting your drive scream for the whole length of the movie, you can buffer the movie to hard drive in couple minutes before the movie, while you are preparing yourself some snack food for the movie experience.
Hard drive space is 8.7GB/EUR if you buy the western digital 640GB. So you can store the equivalent of 80 DVD disks on such single drive with much less hassle.
The first isn't important in terms of noise since the idea with an install is to get it over and done with. The third you can control the speed of the burner in any good app. It's the second one I don't know much about, does this vary from drive to drive, or are they all smart enough to play at low speeds? Is there much of a difference in how much noise escapes each drive? Is there much of a difference between slot and tray drives?
You forgot the 4th: Some programs require their original DVD in the drive when they are being run. This is braindead and should be forbidden. Just look at Steam to see how to do it right. But luckily it is often possible to use virtual dvd images instead.