Part of your issue with pure pos system with no checkpoints and full premine is that the fund holder of all the coins or tokens has nothing at stake to loose.  This is fine when there is no value in the coin but as soon as there is value the incentive to double spend and cash out on your large holding while being able to double spend becomes too much that it will be done.  Nubits ran into this problem with the need for 51% or more on votes to pass motions on buy backs on the coin being approved by the same 51% stake in the coin holders.  No one has a pure pos system that works, peercoin is due to remove the centralized checkpointing in the next version 0.6 and I have not seen any other pos coin achieve the necessary distribution to be confident the network will not be at risk by removing the checkpointing. 

Any pure pos system one has to ask about distribution methods and how the market value has been determined, has it been through true market fluctuations over time or has it been inflated by a few holding coins off the market just to push the price high?

Trust has to be earnt, by a premine and central authority how has any trust been earnt to invest in the cryptocoin?