DPS isn't the end all though. Reload speeds, versatility in regards to ranges of combat, ease of use all play a part in a gun. The TRV ideally might have the highest DPS, that's considering every round required to kill someone hits them. That said, the NS-11 really on shines for the TR. Both the NC and the VS have weapons that either functionally perform like the NS-11, or beat it outright (higher RoF AND matching/lower recoil values.) Only the TR medics don't have access to a 652 RPM rifle with a mere .22 recoil on each shot. For comparison's sake, the average TR weapon has a .27 recoil on each shot, and that's actually fairly big. The NS-11 is also single direction in it's horizontal pull, where as all TR rifles outside of the TAR and TRV are multi-directional. If one knows how to counter recoil, they'll want the single directional pull weapons for their consistency. Overall, not a bad gun, but definitely replaceable. It's not OP at all, just very reliable.
It has a way better cone of fire for an automatic weapon IMO. http://forums.station.sony.com/ps2/index.php?threads/video-ns-11a-weapon-review.78159/
Hmm, maybe. I haven't noticed, to be honest, but my main is NC, so I burst fire by habit nowadays. On my TR character though, most of the starting weapons feel more effective than the NS-11A -- significantly so in close combat, and slightly so at midrange.
Well TR weapons are good in close range because of the fire rate. Not a lot of them perform well at longer ranges if you want to sustain fire. I think the NS-11 fits that niche perfectly.