i would prefer to always use Linux, but my company gives all the engineers Macs, so that's what I now use. I miss Linux deeply, but maintaining two dev environments, not to mention context switching wrt key commands, drove me to the brink.
On the positive side, OSX is still unix. MacVim rules. OSX fixes some of the Linux issues that drove me mad (like power mgmt & plugging in an external monitor). And I've gotten around the screen resize issue mentioned here w/ a little 3rd party app called sizeup... Not ideal, but a workable solution that keeps me productive on the platform.