Hi Don,
In fact I noticed the Photoshop noise reduction filter quite lately and applyied it to some 1600 images. Then the day after I just went curious and tryied the iso 3200 at a sunset hour, i,e, enjoying a surplus of light, by pure coincidence. It was a plain technical test, not an image making situation, for which I adjusted the camera to widest aperture priority and fixed iso 3200. The woman was selected for posing still, without me being aware of the speed. I did during that hour some other 10 different images in my way home, and the woman one resulted the most aesthetically pleasing one. The other compositions were quite ugly, not just noisy.
In fact, at real night street hours, I take for granted that there will be much more plain black areas in the pictures, being the 3200 noise perhaps unbearable. On the other hand, wider aperture fixed focal length "legacy" (I explode in laugh by the term) lens, will enable lower iso levels, like 1600 and all the way in between to 800.
Thanks & Cheers,
Ruben