OpenCL and general graphics performance is not up to par with Windows systems.This is because the graphics drivers is not that good, and it wasn't until Leopard that Apple had good graphics support. The nvidia drivers are even worse (osx gaming on my MBP is horrible, mining even worse even though it has two gpus). If enough people pushed AMD and Apple, maybe something will happen...
I would suggest boot camp, and switch to windows for mining during the night when not using the computer. Or a linux usb stick to boot from.
Apple has developed OpenCL. If they don't support their own invention now, they will never. Just face it, Apple Computers are not for the working kind..