Nano's do lose water through evap quite profusely on the norm and because of the small size of the water column this aggravates the saline content quickly enough to kill that's the reason for the ATO.
If the constant mixing and water changes and checking salt content all the time does not bother you go for salt. Build, buy, or acquire the ATO and set it all up.
Challenges are what this hobby is all about for me, I like them so I generate them on my own by making things difficult sometimes. If your like this then I suggest salt over fresh. If not go fresh over salt to make things easier...
Either way It's all about personal taste.
BTW you still need to buy more saltwater eventually (a single gallon here and there) or make it yourself since you do have to do water changes occasionally.
"You Killed Fritz!"
Bakshi references are always cool!