It's not that your camera is bad, it's just that my camera is full frame (and therefore expensive. I dropped $1,600 on this body). Even on my D5100, an $800 camera and entry level cropped frame DSLR, I wouldn't allow myself to go above 800 ISO for paid work. If you're shooting on an entry level DSLR or PaS camera you're not going to get good ISO performance, period.
Plus it helped that the light was good already in my shots. ISO will never fully compensate for terrible light. If something is dark to the naked eye, there's a good chance that it'll be grainy if you're trying to use ISO to get a decent exposure.
Edit: will post exit later. On phone.
Also I dig that B&W. Could've gone deeper on the blacks but the foundation is there.
Edit2: Okay, so the one I thought was shot at ~1k was actually 320, but the first one was definitely 6,400. At 100% crop:
I think the camera's biggest strength is that it doesn't have discolored noise. The noise still manifests itself as grain at 6,400 (albeit not as bad) it just doesn't produce nasty looking banding/random coloration and whatnot.
