I fail to see any benefit if you're running in a windows VM all the time. You get all the problems of windows and you have to maintain a mac OS on top of that.
Even if the mac file system is better, I doubt the windows VM will be reading faster from it. Doesn't it use an NTFS virtual drive? I'd be more inclined to believe you take a performance hit from running in a VM. And I suspect you'll find a much faster PC for the same price as a mac.