Just jumping in here. I have as well a 27" 2017. Full 64GB Memory and a 1TB disk. Started to clean up the hard drive, because it was getting full, but managed to get 50% free. I mainly use it for photo editing with Lightroom and Photoshop and it is a bit slow in starting up these programs, but when it runs it is working fine. Just gutted that there will be no more updated and even more that there is no 27" model anymore.
I am considering to upgrade to a Mac Studio, but one of the cheapest models will set me back 2'400 and then I still need a monitor with camera for another 500. Advantage is that I can deduct it from my taxes, since I will be using it for work as well.
Although it is working fine I know that the Mac Studio will be a considerable upgrade. Just do not know how to convince the Mrs. that it will benefit her as well while watching Youtube vids.