I'm like Simon and run an old 2009 Mac Pro that's been upgraded, though I stopped at the hex-core Xeons, plus I've got an RX580 8Gb in the mix.

As an audio workstation, it can handle pretty much anything I care to throw at it, including orchestral mixes in LPX (10.5.4 in my case) etc etc. It also works pretty well as an video box, and can run DaVinci Resolve 17 at FHD with some effects, though it starts to show its age with 4k video or if you start using video effects too heavily.

Plus the other caveat is that it has pretty much reached its end of life with Mojave (10.14.6) so as Apple continues to make the world look like an iPad, and developers who want part of that market are forced to adapt, this box will get left behind. Eventually, probably in the next year or so, many of the leading developer will likely drop back compatibility for Mojave and start requiring Big Sur. Then you will have the choice of staying with what you have, or moving on.

Personally, I'm going to hang on as long as I can. Not only am I cheap, but the future looks like M1-land if you are tied to an Apple (and I do have some stuff that is Apple-specific), and they will only get better and faster and bigger, and then some of the other pieces will hit the second-hand market and then we'll be good to go. Until then, I'll make do with my mid-2012 MBP and the old Mac Pro


.. mark.
(BiaB 2020 Mac; macOS 10.14.6; MacPro 5,1 56Gb 2xHex-Xeon RX580)