This whole thing is so funny (unless you are one of the investor). Dave has provided verifiable scientific evidence why this thing can't possibly do what the claim, and their entire rebuttal to date is essentially that Dave is too stupid because he isn't a PhD and thus can't understand their laws of physics defying breakthrough. As pointed out, it would be stupidly simple to prove their side. If they really are making these things, then they absolutely must have a working prototype they could send out for reviews.
As for scam or not, there really are two choices. Either they are naive and don't understand what they are doing, or they fully understand that the science is against them. Given the high level of education they claim, it sure seems like they should know exactly what they are doing, in which case there's no doubt, it's a deliberate attempt to defraud people with a product that cannot do what is claimed. There's really not much grey area here.