Considering the topic of discussion, how sure can you be that archive.is will still be around in a year? Three years? Ten?
As much as I tried, all I could find about it is that it's run by one guy in Czech Republic who's paying $2000/month out of pocket for hosting, and apparently dislikes Finland.
http://archive.is/robots.txt doesn't seem too bad, it looks like you could slowly inhale everything... in theory. There are no sitemaps (they're there, but empty placeholders); you have to know the site name to be able to get a workable list.
I think http://www.webcitation.org/ might be better in that regard since it's a consortium of "editors, publishers, libraries". See "How can I be assured that archived material remains accessible and that webcitation.org doesn't disappear in the future?" in their FAQ (http://www.webcitation.org/faq). Although from my perspective it seems to be more geared towards academic use.
As much as I tried, all I could find about it is that it's run by one guy in Czech Republic who's paying $2000/month out of pocket for hosting, and apparently dislikes Finland.