I found the Boston Metal link particularly interesting. If you consider it, combined with a small form factor nuclear reactor, you could build an iron ingot producing plant right on top of the deposits in places that would otherwise be forced to ship ore out for external processing.
They're both interesting, but the aqueous approach has some advantages. Keeping materials working at extreme temperature is difficult: basically anything above 1000C gets very hard. And a low temperature approach has the potential very big advantage of being highly dispatchable, since it would not have to be kept running to keep from freezing up. Dispatchable electrochemistry is like half a battery, just great for dealing with intermittent power sources like renewables.
The second link is interesting. I've only seen the paper on the old Norwegian pilot plant before that slide show. The Norwegians were dealing with Iron Sulfide waste from copper mining as the feed stock. Being able to directly reduce solid iron oxide is probably better.
I have also wondered if you could use the iron rich gangue from bauxite mining as a feed source.
