Thanks to that experiment, I gathered my resources and traded in my 7D - as well as nearly all of my lenses - and upgraded to a Canon 6D at a reduced price.
I was specific: I wanted a camera that had the best noise reduction and capabilities for night photography. For Canon, the 6D was the body to for that. My old camera's highest ISO rating was 12,800; the 6D, in comparison, stops at 102,400 ISO.
The camera would need amazing noise reduction capabilities if Canon felt that 102,400 ISO was the point of no return for overwhelming noise.
It didn't matter. I only ended up needing an ISO of 8000 when I went up last Wednesday. The fact the 6D also uses a full frame sensor instead of cropped also reduces the noise, as well as the amount of surface for light to expose on.
Using the same lens, the same exposure time (1/125th), and the same f/stop (1.8), at a higher ISO rating (I never ventured beyond 6400 on my 7D) I got this:
Barrhaven - South; Woodroffe towards Strandherd Drive.
There was no sheen of colourless grain; blacks were blacks, and lights were full. There were many, many more sharp images than last time, and while there's noise, it only shows up as non-destructive, small grain that blends in with the colours of the image. It's noisy - but in an absolutely non-destructive way.
I was even able to try some vertical straight-down shots:
Merivale Mall, Viewmount Drive. Light from the blue 'M' logos bleed out onto the ground from the building, as does red light from the large Harvey's sign on the restaurant.
Strandherd Drive; looking straight down on the Barrhaven Wal-Mart and surrounding Chapman Mills Marketplace. White light from the parking light standards dilute the orange-lit RioCan Ave as well as fall across the roof of the buildings.
Of course, I had my pilot fly me at a much lower altitude - 2,500 feet rather than 5,000 feet as last time - so lights on the ground probably came out brighter. I was also impressed by the way cars and vehicles appeared - very insect-like, their head and tail lights not very noticeable unless they braked or appeared on low-lit, or unlit, roads. What I couldn't believe is that my camera was actually, despite the lack of light, able to pick out objects on the ground or just the ground in general of areas that weren't lit at all.
My neighbourhood; I can actually see roofs - and lawn lights - this time.
My old neighbourhood. If you look closely you can actually see unlit streets and the tennis court. Geez.
This flight is the one that properly proved that with a good camera you can really make things look amazing at night. I traded in a lot to get my Canon 6D - I only have one proper lens (my 50mm) as well as my fisheye (which requires I crop each image I take with it thanks to the full frame sensor) and it was obviously worth it. Noise is evident but not in a horribly, destructive way that renders the whole flight pointless, and I can focus now on other issues - such as aiming for a slightly smaller aperture, a slightly faster exposure time, and more all-around sharpness. Thanks to both, quite a few of my images had some camera shake in them (though not as much as I expected) and many had very small areas of sharpness due to the tiny depth of field. I tried an ISO as high as 56,000 and even then, while the noise was very obvious, it wasn't destructive - not in any way my old camera was at a mere ISO 3200.
The only difference here is altitude and ISO level. Every other variable is the same - save for altitude, ISO (bottom one is 8000; top one is 6400) and camera body. And the LED lighting on Meadowlands Drive and Fisher Avenue.
This goes to show that night photography, as I'd hoped, can be quite a fun, interesting, artistic, new way to see things.
The accompanying video:
All images here.