> A complete nightmare, and even if you get it working, you wind up with an unstable system.
It's not as bad as that. I built 2 back back in 2008-2009, and they were rock stable-- kernel panics were extremely rare. They also didn't require much in the way of hackery. I put the EFI boot loader on a thumb drive and kept my OS X drive as free of hacked bits as possible. I wanted to be able to hook it up to a real Mac and boot it without issue, and I achieved this goal. Still, I would never recommend them in a business setting.
One of the machines was my daily driver, and dual booted Windows. The other ran OS X Server and was the fileserver in my house. The specs on the server were enough to get the job done, but my daily driver gave me top of the line Mac Pro performance for about $1200.
The only problem was OS updates-- they usually broke something. I maintained a bootable clone of both machines' boot drives, and waited a few days for other hackintoshers to find and figure out how to fix the issues before installing those updates. Both machines ran Snow Leopard for their entire term of service, which ended last year. They were replaced with refurb Mac minis. The hackintoshing was an interesting experiment, but I wanted a new OS without more hackery, supported hardware, and worry-free updating again. As a side effect, my electric bill fell off a cliff, which was nice.