Does it really matter the overall PC vs Mac? Wouldn't a better number be developers on PC vs Mac? I'm on a Mac, running the Mac version of Slick, but develop for Linux. Several others in my company (though no one else running slick, yet) do the same thing..
With Mac having Vmware and Parallels, and the ability to cleanly (well, mostly cleanly), to run X for remote Linux development, Macs are almost the perfect dev machines, since they handle all 3 major OS's cleanly. No more dual/triple booting booting, multiple machines, etc..
All that said, the current Slick is 'good enough' for me. I have to run X anyways for the software I develop.. The only annoying this is the copy/paste between Slick and OSX.. I do drool at the thought of what Slick -could- be under native OSX though. Imagine being able to hook into the new services stuff in Snow Leopard, and the script/editing power of Slick.