on another point, NXT appears to be 100% POS and has not been forked or hacked by anyone to date. Further it Appears that the network swiftly punishes miner that try to undertake dubious activity, like producing dogey blocks.
All PoS coins (including NXT) prevent this "history attack" by centralized checkpoints. The developer has absolute control over the network. If centralized checkpoints were removed it would be beyond trivial to attack the network with no risk and no cost. So PoS "works" as long as you want a centrally controlled and secured "decentralized" currency.