I was an ardent Linux desktop user for years (Slackware, Gentoo, Ubuntu), and the model of OSX for desktop, Ubuntu VM for dev works well for me. I have this exact set up doing Django based work. I treat my Ubuntu VM as an IDE... suspend when I am not working, resume and I have 4 desktops in the same state they were the last time I worked (desktop for test server processes + celery, and logs, a desktop for editing files in vim, and one running FF on the project(s) I am working on).
OSX's desktop experience is so much simpler and straightforward for a lot of things. I loathe homebrew and XCode, and actively avoid doing anything with those tools under OSX (but I know I can fire up a terminal when I need to). iTunes and sync'ing to my iPhone have become indispensible, Notational Velocity / Simplenote kicks tomboy/gnote, text expander, Adium, etc. There are equivalents on linux, but they always lack some polish... I know people think OSX takes away choice and power (like some kind of toy OS), but I have come to be okay with that for the convenience and consistency it brings to the table.
Give me a vanilla OSX install over a vanilla ubuntu install any day of the week.