It's been down for a day, and may be down for a few more. Looks like "Just build your own Internet" isn't a viable option for internet communists, everyone must learn of their peaceful ways by force.
Trying to get to Saidit redirects you to Saidit's Subreddit, in a sad state of affairs.
EDIT:It's come back up since then. Updates in the link.
Nah, in my experience you can get away with saying almost anything here as long as you're careful about how you phrase it. Coming here and screaming "Sieg Heil" isn't going to fly, but making real arguments against mass immigration or against feminism is very commonplace here.
Basically, don't be a sperg.