PIVX is unlimited and has a constant 4.8% staking. That makes it the same as cash when you think about it. Cash money is being printed without limit (unlimited coin emission of PIVX) and the only thing that prevents cash from being printed faster is how fast their printers are (4.8% staking rewards of PIVX). Value is given by demande, offer and how much is available. The only thing that regulates the last point (availability) is the low 4.8% staking rewards (which can still be compared to cash money and their printers that regulates how much is being printed).

Masternodes, as explained by someone else, adds failure points to the network and gives power to the people owning them which creates a political scheme (Isn't what we're trying to escape with Cryptocurrencies?).

PIVX is just another Anon coin with staking rewards like any other. If you think it's the first one haveing the zero knowledge proof, think again. BLITZ was the first PoS coin to have that.