I'm definitely considering both. But I'd definitely hold off on buying the HDMI NES for a while if I knew how good Retron 5's NES emulation was, because the NES functionality is what I'm looking forward to above else.
The price difference might well be enough to where someone who only wants to play NES games would still go with the R5. Is there a price quote for the hdmi NES yet? Well over $100 I would imagine.