I've been using High Sierra in Qemu for a few months, and it runs really well, there are a few drawbacks. 1. I haven't figured out how to pass a PCI Firewire or XHCI USB card to my virtual MP, yet, in a way that they work correct. 2. I only have a 8 core 16 thread "Penryn" cpu, as I can't get my EFI firmware to boot when I select a CPU that would be "supported" by about this Mac. 3. Can't figure how to pass my Apple bluetooth. Now the befits: 1. Boot screens for my RX580. 2. "native" support for M.2 NVME booting. 3. unmodified version of the macOS. 4. I can run Windows, Linux, and the macOS all at the same time, passing each on 8 cores and 16 threads, and the Linux host will load level CPU use with no real performance hit. 5. I can upgrade my system. 6. My system is open source, and I'm only really limited to how good of a coder I am, as to what I can make it do. I passthrough a OEM Apple 802.11AC wifi card, an M.2 960 EVO, and an RX580, as well as any AHCI drives and USB( sans Apple bluetooth ). I'd love to take the "Pepsi challenge" with folks with real Apple hardware, as far as what works and benchmarks, tho if you have a 12 core 24 thread machine you will likely beat me out, as well if you have a 1070/1080/Titan XP, I'm sure you can put up better numbers than me. However my system costs around $1200 to build, and I can upgrade my CPU, video card, and ram.