I'm in the same boat. I have two Mac Pro 3.1 with dual Xeons and 32 GB/64 GB RAM. These are still very powerful computers and I love their internal build. Still, in order to run Mojave on them I had to resort to the patched version. These machines cost over $4000 each in their original configuration, so I'd expect Apple to show a bit more respect to their loyal customers. It's ridiculous that the same machine can run a competing operating system without any problem.