The KSG is an awesome concept, and one that I hope leads to further refinements and developments from other companies.
Setting aside for a moment the reported reliability issues with the KSG, the one thing I am fundamentally unimpressed with is how dexterity-intensive it is to reload the gun. With a bit of practice, using the weak-hand technique, I've reloaded a traditional shotgun with eight rounds in ~9 seconds.
From what I've seen, in order to reload the KSG, you have to reach way up into the receiver to load it, and it doesn't seem like any of the traditional techniques for quickly reloading a shotgun would work, and I'm unaware of any new techniques that make reloading the KSG as fast as or faster than reloading a traditional semi-auto or pump gun.
While this may seem like nitpicking, I think it's very important for a couple of reasons.
1.) Reloading tube-fed shotguns is the most labor- and coordination-intensive reloading action done for any of the three major types of gun (rifle, pistol, shotgun.)
2.) One of the advantages of the shotgun is the ability to load it with ammunition adapted to specialty needs, e.g., quickly executing an unanticipated select-slug drill.
Granted, these concerns are somewhat alleviated by the relatively high capacity of the KSG in the case of the first issue, and by loading one tube with, say, buckshot and the other with slugs in the case of the second. Still, regardless of the capacity of the gun, it is still limited, which means you have to reload sometime, and opting to use the tubes to categorize your ammunition is going to come with it's own issues, such as remembering which tube is which, and remembering to hit the selector, to say nothing of the fact that organizing your ammunition in the tubes effectively halves the amount of preferred ammunition you have loaded in the gun.
Don't get me wrong. I really like the idea of the KSG. Shotguns have noticeably lagged behind handguns and rifles in the development and adoption of new technologies that make the guns more user-friendly, and the KSG is a large step in the right direction, however, I don't the dual-tube/bullpup configuration is ready for prime time yet.