Guess I have to say things are not that optimistic in PoS. I might give you an example of attacking an ill formed PoS design for illustration purpose in the near future.
That would be great!
One question you might think right now is: Why PeerCoin needs to broadcast checkpoint regularly? Why NXT have that kind of restriction while Bitcoin does not?
I'm not saying NXT and similar systems don't need those restrictions. I'm saying I don't see the problem with having those restrictions and how it's supposed to lead to centralization.