My main question is how can they overcome the power loss in taking electricity and producing microwaves. I am not convienced it will heat water cheaper than existing tankless water heaters.
From all I have managed to research, and the very many related patents that have not to date resulted in product of high efficiency, what you state IS THE key issue. We need to see understandable (i.e. not censored and relevant, intelligibly presented) evidence that the "contemplated" product is tracking to break this technical barrier. JMO