I've been using AeroFS in headless mode on my NAS as well, and it's worked fine so far (the headless mode itself, I think there were a few bugs in AeroFS).
I'll try it again now, however. If they nail the fundamentals down, it'll replace Dropbox for me.
EDIT: Or do you mean custom NAS OSes? Mine just runs Ubuntu.
I used to build my own SqueezeBox Server for years from source, but after a while I just wanted it reasonably up to date, in a stable build, without the hassle. I'd hope that AeroFS would be packaged in the same way so it's not another thing on my list of things to maintain.
