POS is actually more secure than POW.
It's false.
It is a widely spread belief that crypto-currencies implementing a proof of stake transaction validation system are less vulnerable to a 51% attack than crypto-currencies implementing a proof of work transaction validation system. In this article, we show that it is not the case and that, in fact, if the attackers motivation is large enough (and this is common knowledge), he will succeed in his attack at no cost.
http://papers.ssrn.com/sol3/papers.cfm?abstract_id=2393940
This article is nonsense. I remember it was discussed several months ago in the NXT monster thread.