Seeing a lot of talk about connectivity effecting this gun, which may be true to some extent... but I think there is more to it than that.
I am not much of a shotgun guy, admittedly. Never use them in pub lobbies unless I am just messing about. I tend to play Custom Games when nobody is on or I am too tired or not in the mood to play Pub games. Watched a video from Hutch the other day praising the KSG, so I thought I would give it a run in Custom Games just to see what it is all about. I usually just play HC TDM 1v 9 against the Bots on Recruit or Regular(Not playing for the challenge necessarily, usually just to test setups and learn maps. Step it up if I am looking for a challenge.)
I equipped the KSG with laser sight and made several observations during the match. It just seemed to me to be a very schizophrenic weapon. There were times when I would ADS and get kills at a fairly long range, and then others when the Bot would just stare at me before shooting me down. The hip fire on the KSG is poor by design, but even with the laser sight it is iffy at best. Had moments when I ran over hoards of bots, and then others when it appeared I was right on target with the laser only to miss. So it really isn't just the lag or latency, it truly is an inconsistent weapon. Granted I haven't used it a lot, but just as a casual observer that is what I noticed.
The Remington 870 is much more efficient. The range seems to be comparable, it reloads quicker, and is much more reliable when hip fired.