I'm running Resolve 11 on a Hackintosh, quad intel 4770k with no problems. I have cycled through a GTX 780, then GTX 980, and recently an R290x 8gb video card without issues. The nMP were having OpenCL issues early last year with AMD cards, but that's not Blackmagic's or AMD's fault. Apple handles OpenCL on their platform.

You may have also had problems with overheating of your cards (another problem brought up last year), or were running out of memory. Not sure about audio problems, though, and yes, I also felt the interface to be clumsy.

OFX Plugins only, so depends on the plugin author.