I use an 11 inch macbook air as my every day notebook and I do a large amount of development on it.
Unfortunately I don't think there's a very good selection of EE tools for OSX. The selection of cross-platform tools is of course even smaller. I use gEDA, which installs from macports easily enough, but it's an X11 app and the usability is rather poor in OSX. It's completely impractical to do any CAD work with the touchpad, so a mouse is necessary and that really breaks the convence and purpose of an ultraportable notebook. But it's cross-platform and that allows me to work from my macbook as well as my desktop, which runs linux. I've been meaning (since before I got the macbook) to switch to kicad, but I don't expect it to be much better with respect to OSX usability. If I recall correctly though, kicad compiles as a native app in OSX rather than X11 and since it's opensource I look forward to improving the OSX/touchpad usability when I have the time.
For code development I use kdevelop. It turns out that I don't like xcode as much as I remember. Last time I used xcode was the first time I really used a full IDE for any length of time so it's possible that my first impression was skewed. I prefer kdevelop even though it runs in X11 which, again, makes the usability (mostly the scrolling) somewhat poor.
Given some additional options, I don't think I'd do EE work in OSX. The plan was to install linux on the macbook but, open-minded as I am, I gave OSX a chance first. So far (4 months or so) I like it more than I expected and have kept it around, though this is likely only made possible by the fact that my desktop still runs linux and I can always run a native linux app from it on my macbook using remote X11 over ssh if I need to.
So the bottom line is that while I do use an apple product for active daily development, it isn't ideal and I look forward to a better solution. I find myself returning to my desktop to work more often than was intended when I decided to get a notebook to use for work.