POS / PON or POI forging will be use? I prefer POS / PON. But perhaps there are more arguments for POI ?
Our new P-O-I is a new innovative way of forging which I believe will make NEM a more sustainable system. Makoto is writing the white paper and when all the theoretical aspects are considered we will implement it in the core codes.
Would it be possible to implement a combination of POS, PON and POI? I think it would make the system really stable, because POS would give the incentive to invest in the currency, PON would encourage to support the network and POI would encourage to use the currency!
maybe a new forging-variable, which is a mix of the amount your holding & your activity?
the NEM-O-METER

interesting importance ...
Is it sure that importance is not close to PoW ?
Yes as far I've understood it works so that the system analyzes the in and out transactions made from you account. The account which has most transactions will then be the one that has contributed most to the distribution of the coin and therefore has most hashing power. This will guarantee the circulation of the currency.
But we must here remember that it can not solely be POI because it will only encourage trading between the accounts that you've created. There must be a combination of some sort.
Also if POI is to be implemented it will be important IMO that there will be a account/alias bound reputation system.
But the major flaw that I see atm with POI is regarding the fact that you can just circulate coins between your own account and get hashing power that way. If this isn't prevented somehow I suggest that the forging will be at maximum 20% based on POI.
But these are all my speculations, I've got no legitimate knowledge on the mechanisms of POI. Lets just see that how the white paper turns out.