Onion version of the forum can only guarantee anonymity but will still be venerable of DDoS attack to an extent.
Again, I don't think that theymos will buy the idea because of the reputation of the forum. Having an onion version might take the government's eyes to the forum and some kind of legal compliances would be required.
~snip~
You mean the same government agencies that also have their own onion versions? If we go in that direction, maybe Tor and VPN should be banned due to the reputation of the forum - only then would we lose at least 50% of members overnight... because in some (for the forum) important countries this forum is banned.
So that I don't seem like I'm talking nonsense, here's a link to an interesting onion site ->
Link