The G11 only does ~60 damage if BO rifles and FALs do 80, because that's
maximum damage. But if you get a well-commended agent, then 160-180 bravery is very much achievable by mid-game, and then they do mostly the same damage as BO rifles or the various 7.62x51 rifles.
What the G11 has going for it is a very fast and accurate auto-shot. You can shoot it auto at more or less the same distance as everything else's snap range. The aimed shot is a bit worse, though. So if you can stack the necessary commendations, it's competitive with other top-end ballistic rifles and perhaps even better considering it can hit multiple times per shot.
The two actual BO rifles are indeed upgrades, but so marginal that replacing your whole arsenal is usually more hassle than it's worth. I like their aesthetic, so I do use them, but then again I also mod them further.
The UAC rifle I don't like. It essentially shoots a slighly faster, somewhat less accurate auto-shot (kinda like auto-and-snap-shot all in one), and pays for it with weight, poorer accuracy in general, and ammo that costs
a lot. Where it shines compared to the other rifles is close combat, but the G11 in a good agent's hands does so as well, and is noticeably better at range. A Smartrifle has 5-shot autofire, which is a different way to do the same thing, and much better and more flexible snaps and aimed shots. And you have a plethora of other close-medium range weapons that do better than any rifle, so this niche is moot anyway.
The BO Auto-Sniper is good, but doesn't have the TU-flexibility or the autofire accuracy of the rifles. Never really liked it, perhaps I should reconsider.
In the end, though, what psavola says is true. The niche rifles occupy in RL combat is not particularly well modeled in the mod (or other weapons are made stronger than they should be, and thus take the rifles' spot), and once you have more than a few agents, you can specialise and do better than with even the best rifles. Never mind all the oddball weapons that eat other weapons' lunch.