My favorite shotgun is the KSR-35. Seriously though, shotguns get a solid 'meh' from me in this game. Generally if I die to a shotgun it was either a situation I could have avoided or a situation in which I would have died to any other gun. Occasionally I am killed by a shotgun that I never saw coming or couldn't have avoided, but it's no more or less annoying that getting HESH'd or ESF'd and happens far less frequently. For every one death you have from a shotgun user, you probably kill at least one without knowing it. Usually those are the ones you kill and think afterwords "why didn't he shoot back?". I have briefly messed about with the default SA shotty on my Light Assault before deciding I hated it and buying a Blackjack. It's fun for those magical moments when you stumble on a group of enemies that either aren't paying attention or react too slowly, but for the most part it's a lot of trying to set up an engagement beforehand so you don't just get one kill and die from 3 other guys. Even so my potato aim is strong and consistent enough to gift me a free death every few lives or so. To be honest the best indicator that I've been using a shotgun is the spike in my Blackhand kills.
My experience with shotguns has been a mixed one. I tend to find them to be very black and white options, which is why I have some issues with them. Between their power and fire rate, either you get your opponent instantly with a quick burst, or you tickle them and get wrecked. The difference between these two extremes often feels to be measured by no more then a meter. At 10 meters, you get wrecked by the guy with the shotgun instantly. At 11 meters, he tickles you. I find it's this lack on consistency that forms the basis of the majority of arguments both in favor and against them. I really don't like using them, because I find I struggle massively with that range problem, but there are also few things that I find more infuriating when playing then someone who can deal with this range issue on a pump shotgun. So my thought is generally to try and smooth out that performance.
Funny, because they already did that a couple years back. As in, lowered the raw damage and raised the applicable range. (Semi-autos used to be able to OHK on a point blank headshot) I'm not sure they need another "smoothing out" pass, but I do think they could use some tweaks.