I've just read about the development funding proposal, and it seems a bit strange that every miners would be forced to contribute to an organisation. At the same time, I agree that injecting money into development is a good investment for the future. So I wonder if we could make this 12.5% contribution optional without penalizing those who contribute. Here's an idea:
We could add a 12.5% difficulty handicap when mining a block when it does not include a contribution to the development fund organisation. Other miners would orphan blocks not sending a contribution only if the higher difficulty threshold is not met. That means the miners who do not contribute will be getting the same returns as the miners who do, with only a bit more variance. If all miners decide not to contribute, then we just get back to today's situation (the DAA would end up lowering the difficulty to counter everyone's handicap).
In the end funding becomes proportional to the willingness of miners to contribute in aggregate, but the burden is effectively shared by all miners through this difficulty equilibrium.