I recently ordered one of these after lots of research and it seems like there are at least two different chipsets from various chinese sellers in both 4 and 7 in versions. One has DDR2 128MB ram, dual core cpu and says max of 32GB SD max. The other is the same as OP with DDR3 256 ram, quadcore cpu, and 64GB SD max. I would be careful because you can't go by battery life or the model G1000 either because I've seen both variations under G1000. Also it seems like everyone who made a video about this thing has the weaker one. I would hope the better specced one at least runs N64 better.
I will post updates when I get mine, it shipped from a US location and should take too long.