@herzmeister, first let me quote jtimon from his post introducing the idea of Freicoin over a year ago. He did a good job listing the advantages of a demurrage currency, and more importantly included links to the relevant economic theories:
Do I think a global demurrage currency is a good thing? Yes, for the same reason that any global currency that is free of control from central bankers is a good thing. I feel that the local currency movement is misguided in trying to fight globalism, and the lack of similar restrictions on Freicoin is a good thing. Of course it is an opt-in proposal, so anyone can use it (or not use it) as they see fit.
Demurrage does not do anything specifically to fuel consumption--one could just as easily buy bonds, equities, bitcoins to get rid of unwanted freicoins. It does however incentivise long-term thinking and the acquisition of real capital when compared with high-interest currencies like deflationary Bitcoin or inflationary fiat. Here's a classic example:
Whereas interest promotes the discounting of future cash flows, demurrage encourages long-term thinking. In present-day accounting, a forest that has the capacity to generate one million dollars a year every year into the foreseeable future is considered more valuable if immediately cut down for a profit of 50 million dollars. (The net present value of the sustainable forest calculated at a discount rate of 5% is only $20 million.) This state of affairs results in the infamously short-sighted behavior of corporations that sacrifice (even their own) long-term well-being for the short-term results of the fiscal quarter. Such behavior is perfectly rational in an interest-based economy, but in a demurrage system, pure self-interest would dictate that the forest be preserved. No longer would greed motivate the robbing of the future for the benefit of the present. The exponential discounting of future cash flows implies the "cashing in" of the entire earth as opposed to an immediate wholesale liquidation of our remaining resources.
So one could say that the type of consumerism encouraged by demurrage currencies (investment in real capital for increased production) is actually beneficial.