Personally I sit in about the middle of the two sides arguing in this thread, I am pretty much indifferent to the KSG.
I would not spend the time trying to argue against someone who purchased a rifle and liked it, even if my feelings were that it had some issues and I would not own one.
I am not against various polymer components for some pieces on rifles. However I do prefer as much metal as possible.
Regarding the KSG, I spent a lot of time looking at it and researching everything I could find. I decided against it for myself for two reasons alone:
- The plastic molded components especially along the seams are badly mismatched, this is more of an aesthetic appearance thing, but it makes the rifle look like cheap chinese equipment. I've seen airsoft that looks better molded. However, I have the same complaints about some of the other polymer products on the market, for example the MagPul products like the MBUS (the MOE USA versions!). I have a few sets and will never buy them again because of the terrible molding seams (requiring cleanup before you can use them) and cheap construction (try snapping them a few times without forceably holding the release lever open and the plastic catch will wear down allowing false flipping under high recoil), I am replacing them with MI or Troy or similar aluminum sights which are only ~$50-75 more for a set.
- The design of the KSG has the ejection and feed through the same bottom port which results in a more complex mechanism, guaranteed to have a higher ftf/jam. This is prone to more issues long-term than the simpler mechanism used in pump-action Moss/Rem. While this may be fine for some people who are into short-term ownership/trading/throw-away/disposable income, I purchase all of my rifles for very long-term ownership (my oldest being a 42 year old Cooey 39 I was given when I was a kid). One of my criteria for purchase is will the rifle last through a long shtf/war/depression, and imho I wouldn't take the chance with the KSG.
For the price of the KSG, I would want a lot more gun than what it gives. I can buy a lot of Moss/Rem shotguns or a really nice Moss/Rem for the price of one KSG. If the KSG were ~$400 tax-in, which imho is its actual value, I might consider getting one for fun.
That being said, I would never discourage someone else from buying a KSG. Although if I were asked which shotgun I would recommend to someone, unfortunately this would not be one of them. For those who own and like the rifle, more power to you, enjoy the rifle.