I promise I'll get to Mintcoin vs. Blackcoin but a preface here:

A lot of people in the crypto/libertarian community likes to talk shit about central banks and how we need to revert to some kind of gold standard. What's often not discussed are the finer details: For instance, the world's central banks have presided over the money supply through the most radical expansion of wealth, higher living standards, longer lifespans and the most radical decrease of infant mortality in human history, through the course of the 19th century. They've also presided over the largest and deadliest wars in human history (although not necessarily as bad as they could have been given the technology, and for all their brutality, not necessarily more brutal than wars that had gone before).

Well. What this means is that no one with a knowledge of history can discount out of hand the idea that all economies are a non-zero-sum game in which the money supply needs to grow and contract to provide the necessary incentives to save or stimulus to invest. And so anything with a flat rate of interest or inflation is naturally a bit suspect, because human affairs just don't work that way. Shouldn't BC generate more money supply if more business is being done in the currency and people want to borrow it? Shouldn't MintCoin give less interest if it's apparent that its inflation is running out of control?

What we think we know is that Bitcoin itself is too prone to hoarding and too deflationary in nature. Therefore a proof-of-stake seems like a sensible idea, or at least a valuable experiment. The question for me about MintCoin is why that stake should be higher in the beginning. MintCoin's strategy for lowering stake by the year seems arbitrary and may become counterproductive at any point where the currency really begins to take off. It's an incentive to hoarding, at least for the first 5 years. And it's not an incentive to financing after that.

Is BlackCoin striking the right balance because it will always keep a 1% rate? Probably not exactly. However it's a lot closer to being a long-run fair bet than something that's going to arbitrarily dictate reduced interest rates annually with no regard for how many people adopt it or how they use it.

[ed] and it's worth mentioning that multi-pool mining for other coins is basically a kind of carry trade arbitrage that's already being carried out in BC.