Fast-firing multibarreled guns aren't new, the Gatling gun dates back to the 1860's, and current electric guns can fire thousands of rounds/min. The article states the Uzi fires 3,000 r/m, which should be about 600 r/m. The GE minigun fires 6,000 r/m, and adding more guns or more barrels would increase the rate, but ammunition is heavy.
I suspect there's a lot of hype combined with the reporter's ignorance in this story.
All the weapons you listed can be reloaded at the site. The Metal Storm is a nothing more than a long distance, single use shotgun.