I've thought about this, and it's an inevitable thing that comes to what is created with the type of mindset I have for this add-on. There's not much I can do aside from extend the general range of everything, which wouldn't really even help all too much. What you say, however, still applies to even your own pack, although to a somewhat less extent. Either way, people with shotguns will stick to the close-range, and people with sniper rifles will stick to the long-range, unless they're both looking to easily die - it's kind of the whole idea of using a range-restricted weapon.
i have never seen this happen
shotgunners tend to bum-rush even snipers with all the cowardice of a freight train, and they actually win roughly 20% of the time
snipers in close quarters can headshot people easy if they know they're coming and the opposition doesn't know they're there, but if they forget up the first shot they're royally boned
weapon selection in tier+tactical is more like a 'personal preference first', 'implications later' kind of deal