Mining costs are ramping up with a speed of lightning and reward for block finding is going down. At some point there is no way to enter this economy since there are "top miners" who will simply outmine you.
"Free Entry" does not mean "low capital requirements".
http://yadayadayadaecon.com/concept/free-entry-and-exit/I fail to understand why an attacker has to choose which chain to participate in.
The built-in fundamental premise of PoS is that the stakers will mostly behave themselves because they have a lot of stake. Ultimately, if they misbehave the "trustworthy" will roll it back to their preferred chain.
The mechanism by which this roll back takes place in NXT is through trusted peer lists and a 720 block fork limit. (Not through formal "checkpoints" like I expected.)
So PoS does not achieve trust-free globally decentralized consensus, which is the entire point of the N@S criticism.
http://download.wpsoftware.net/bitcoin/pos.pdfThough I think I'm preaching to the choir...