Not sure about the DVD-RAM discs themselves but I've got a few first gen CDROM drives which used caddies to load the discs. It was an absolute pain to have to mess about with them and for some reason even though they've got a shutter, they'd still manage to collect dust and other crud inside.

A big disadvantage is that it used to be/still is that only the single sided discs can be bought without caddies. The double sided ones were all permanently mounted inside the caddy. Another thing is that you can't normally read DVD-RAM discs without a DVD-RAM drive but as it's only to be used as a server backup then you're pretty much going to be reading them on the same machine.

But I agree with everybody else. Go for DLT or Ultrium if you can afford it. It's much more reliable and stores a lot more than a DVD-RAM disc. How big is the disk in the server anyway? If it's bigger than around 4.7GB then it's going to be annoying to have to keep swapping discs.