I'm a Mac guy myself. When I started getting into black hat seo, I used Parallel to run my apps, but I was never 100% satisfied. It was not very stable, and it wasn't fast enough.
Bootcamp wasn't an option, because I wanted to let the apps run in the background while I do my stuff on the computer.
So, I decided to purchase a cheap, but pretty fast Windows laptop. Up to a few weeks ago it was a perfect solution. But then, I got limited by my ISP's monthly bandwidth limit, and by my connection speed. Plus my router would shutdown every now and then when I was running several hundred of threads at the same time.
So, finally I decided to get a VPS and installed all my apps on there. I got a VPS from XSServer.eu and I'm very happy now. I can leave xrumer and scrapebox running 24/24 without worrying about bandwidth. Plus, I can sell my windows laptop since I don't need it anymore. The Remote Desktop app in Mac works great and doesn't slow down my computer.