Trent from BigchainDB wrote a really great article called The DCS Triangle which suggests decentralization, Consistency, and Scale being the three things different protocols can optimize for. As you say, there are also degrees of each of those, and the article gave me a good understanding of which trade offs are even possible.

Trent also reviews #IPFS in his write up. I'm very interested in what happens with it as it doesn't have anything related to currency built into the system.