Thank you for pointing out that
monetary inflation is not the same that
price inflation. I didn't know the correct way to mean one or another.
I think this price deflation may not disappear. It is true that we can't measure the current price deflation of bitcoins just by looking at its USD dollar price, because USD have an increasing price inflation. The point I wanted to make is that you can have price deflation even with monetary inflation. That's what is happening now with bitcoins: the falling dollar is not the only cause of the rise of the bitcoin.
We could even have price inflation with a constant monetary base if less goods are traded every year (negative growth). Let me think about something that could cause a global negative economic growth...oh, yes, a falling EROI, for example. When people say that bitcoin has a built in deflation they mean that when the bitcoin monetary base is completely issued and thus constant, there will be price deflation
if the economy keeps growing.
Price deflation can encourage hoarding and make trade harder (because the medium of exchange gets out of the market), but what you want to fight is hoarding and not the deflation itself. Demurrage can prevent hoarding even in a deflationary context.
Demurrage has another economical advantage. It would make more enterprises profitable. To calculate the profit, you must first discount the interest cost. If you suppress the liquidity premium with demurrage (not the risk premium), the financing costs will decrease. In capitalism, all kinds of capital tend to be as profitable as lending money. If, for example, renting houses becomes more profitable, investors will construct more houses until the profit becomes the equivalent. If there are "too many" houses, the price of houses will drop until they become as profitable as money. Money is the only true capital.
For more on this (sorry if I repeat this links too much):
http://en.wikipedia.org/wiki/Freigeldhttp://finanzcrash.com/english/aberrations.html