I went back to re-read the entire thread to draw some conclusions, and this stood out the most really. While the Mac Pro may not be the absolute fastest now, and especially in 2-3 years, in reality, what I do with it won't really change too much, so if it's more than fine now, it will be more than fine in 3 years the same. It's not like I'm going to keep chasing the latest Canon cinema cameras, or shoot in 12-16k or whatever. For photography it's already plenty, so I'm only concerned with video. And I just don't see that changing all too much. I am looking at PCs now with the AMD 5950X, and yes they are a bit faster now, but in 3 years? Same deal - they also stay the same. I could change the GPU on them, hope that Windows gets better, dunno. Advantage with PCs? Faster now a bit, down the road, not sure the benefits. Downside? I have to leave the macOS system I'm used to and that also ties into my personal devices - iOS, etc. The PC would be an island basically, disconnected from all my other devices. That's a big downside. And in 3 years time, $10k MacPro vs $7k PC - both will ether be replaced or not. Both will run at the same current speed. But if in 3 years I go to an ARM Mac Pro and macOS, the transition from a PC would suck. In other words to go to a PC now means really 2 transitions - one now, and one when I get ARM Mac later. Just thinking a bit more practically. Computers are never really investments, more like cars.
I think whatever choice I make - Mac Pro or PC, I would have to stay on that platform for 10 years for it to make sense. Meaning if I go PC now, I will stay on PC for 10 years before going to another Mac. Moving back and forth is too time consuming for workflow, hardware, ecosystem, etc.