...Am I right here ?:"When writing to a DVDRAM with growisofs I will get a filesystem identical to that of a DVD: udf or iso9660."
Or you can make an empty placeholder on hard disk, losetup it, format to your liking and burn it. I mean growisofs is actually a recording program and formally is filesystem neutral. But it does treat mkisofs output in special way, so you might get an impression that iso9660 is what you "get"...
I heard, that using ext2 or such will kill DVDRAM soon, since there are sectors (blocks? or whatever it is named ... sorry, I am not a native English speaker...) constantly written to, so they will die to soon since there max. write count has been reached.
And so would read-write mounted UDF. It's definitely good idea to mount *either* with noatime, but otherwise I don't think that ext2 would "wear out" the media faster than UDF. Even safer approach would be to keep media mounted read-only for most of the time and re-mount read-write when you actually intend to manipulate data. A.