PPC (peercoin) obsoleted by NXT? PeerCoin has a Proof-of-Stake concept (and a small portion of Proof-of-Work), to secure the network. NXT is using only POS, which makes it even more energy efficient.

Will NXT render PPC (PeerCoin) obsolete? Or which disadvantages does NXT have in comparison to PPC, except for PPC being older and therefore being more established.
One could suggest that PPC is unattackable by currently known methods because of its hybrid PoW/PoS model.

NXT can be theoretically perpetually DoSed or at least hampered by DDoSing each successive forger since the network frequently knows with high certainty the IP of the next forger.

The most likely case is that no properly written cryptocurrency is generally attackable.  I have found no evidence of network attacks, but I'm not as deep into the communities as others.

From very far away, they are indistinguishable: both slower than Ripple and less prestigious than Bitcoin; they're market capitalizations are evidence of those facts.