Well, between this, the Magpul Flashlight gun, and the KRISS, I'm just glad there are some people out there developing some new ideas, or at least a good twist on old ideas. More of the same old same old isn't good! I like anything that has some moving parts, and makes you go "How the crap did they do that?"
It may have some issues, maybe they should take a hint from Magpul, and add a little polymer window to the sides of each tube so you could see how many rounds you have left. I'd also make the tubes different colors, or at least have different colored bases so you could load out with different rounds as they discussed, but actually know what tube your on. The thing I'd be more concerned with, is if the tubes need to be loaded outside of the gun or if you could "re-up" with loose shells.
Zhur