One important fact about the proof of stake inflation model that PPC employs is that it does not transfer wealth from holders of the currency to others who are creators of the currency like government money does. With PPC, you can only create the currency in proportion to how much you hold. It is best that the holders of the currency control the protocol and the chain, unlike proof of work coins where there can be a conflict of interest between miners and users. As the BTC block reward goes down, miners will want substantial transaction fees, but users will not want to pay it. The miners will decide what fees to charge, not the users. With PPC, miners do not receive transaction fees (they are destroyed, which is deflationary), so they will have no reason to try to extract larger fees from users. There is only incentive to make the transaction fee high enough to protect the network from spam, which is as it should be.
Finally, very soon PPC will have lower inflation than BTC as you can see here:
https://bitcointalk.org/index.php?topic=288386.0Currently PPC has 19.3% annual inflation compared to Bitcoin's 15.1%
