I would say their wattage claim is completely outside the realm of possibility. 50MH/W?  Thats nearly 3x the best FPGA designs and 25x current efficient GPU.

I doubt even a custom ASIC would be 3x FPGA in terms of power.  Maybe 50% to 100% better but not 3x.

I also find the fact that their first prototype just happens to be exactly 1GH/s to be very scammy.  They just happen to find the parts that magically work out to 1GH/s.

The price is equally implausible.  Well outside range of FPGA manufacturing cost (much less retail price).  Hell it better than the best video cards (which have the advantage of volume in the millions).  The only thing that could come close is a custom ASIC but if you developed a custom mining chip would you price it that low.  Hell at $800 it is an amazing deal and if not a scam would completely undercut any GPU miner.  ASIC would have huge R&D costs to make up and generally you don't do that by undercutting your competitors by 90%.

Not sure what you see as not being outside the realm of phyiscal possibility.   If anyone wants to put a bet out there on this being honest I will take the otherside.