I beleive devs should be compensated for hard work.  I would suggest that there is closed community where devs would get portion of profit. E.g. 2% of mining profit.  You may leave it as optional,  just like boolberry opensource miner. And gee,  I would pay Wolf extra fees for his tweaks if possible.
I am against upfront fees, I prefer sharing the profit. Perhaps it could be implemented through default mining fees or by using special pool with % of mining profits gearing toward devs.

And please, no "windows only"  editions.