NS Smg worth it?

[BloBBloB]

I've planned to get a smg for some time now, and seeing as it's 1k Certs (and seeing as I'm a pussy) I'm planning to buy one with sc. But I've heard the NS one spreads to other characters if you buy it with sc, so perhaps that's a better option. Unless someone can tell my why Sirius/Blitz/Hailstorm is so much better as the persons I've met say :P

Thanks in advance.