Edit: Scrap that. I just found out that notifications aren't able to be archived :(
I heard that some stuff can still install via SpotPass in the background without your knowledge. I'm not sure how true that is, but I do know that since the notifications are sent through SpotPass, you might also have some news articles that need archiving too (and their are region-specific articles too). I have a 2DS too as a secondary console, so I dumped my data from it as well just because I have some Australia/New Zealand exclusive ones.
Ohh, I just found out that notifications can't be saved into the archive which is sad. I thought they could but I know now that they can't.