What is the benefit of adaptive block sizing?
Mostly it prevents rapid spam attacks and also high orphan rates when txs initially accelerate on the network. Additionally, it provides a mechanism to reduce inflation through blockreward penalty (although we capped that and are working to optimize that section of the code now).
There are downsides, namely that it allows miners to basically control the size of blocks, which the Bitcoin core devs don't like. gmaxwell thinks it should be dumped, smooth wants to proceed with it and see how well it works for us. Less inflation means high price vs fiat typically.
