Yea, I don't know a whole lot about Vanillacoin, but I'm pretty sure it's just taking a Bitcoin 0 conf transaction and using a locking mechanism (which may or may not have security issues) to just visually credit your account faster.  The transactions all still have to be put in a block if you're using a blockchain system...you didn't just gain infinite TPS from nothing.  All PoS systems that don't die will eventually switch to deterministic block validation anyway, thus making that 0 time thing irrelevant.