and last.: ''ASICs are so specialized that they produce nothing other than Bitcoins and to me this is the biggest problem with Proof of Work. '' - no. it is its biggest advantage. Optimal money, maximization of money-ness is where utility for anything else is minimized. Note.: BTC is only money, and asics do nothing but btc. Google for ''under the microscope true cost ''. When I say POW is the cheapest I mean cheapest then everything, not just PoS but also the traditional double-entry centralized-ledger book-keeping hierarchic system we call fiat.