When it comes to controlling test instruments, MacOS has very little support. It's all Windows and some Linux. Only National Instruments supports MacOS through LabVIEW. I monitor the LabVIEW e-mail list every day and even there, I see very few MacOS users. NI made a plendge long ago to alwasy support the Mac on LabVIEW because that's where it started.
I know this thread is about LTSpice for the Mac, but since it is about LTSpice I thought I should mention there is a new book out- The LTSPICE IV Simulator" by Gilles Brocard published by Wurth Eletronik. I got mine yesterday, so I only have first impressions, but it looks really good. You can get it here. There is a TOC here
I'm surprised nobody mention Matlab--I use that on a Mac all the time.
I also use Python for automation of instrument control and compuation--it seems more streamlined and it's quicker to develop code than either Matlab or Labview IMO.
Gerbv is available for looking at circuit board artwork files.
The latest remote desktop app (for windows) available on the Mac app store actually works better than the windows version (there's a bug on Windows RDC that makes it difficult to use the Microcap simulator.)
Microsoft kindly makes Office, Outlook, and Lync available for OS X.
Windows has a number of deficiencies that hinder productivity compare to OS X--at least for my work flow.
Crashing is a non-issue for both except on occasion when I'm doing memory intensive computations on Windows. When Win7 runs low on RAM, it deals with the situation very ineligantly and the whole system nearly freezes. It's not crashed, but it's so slow, I have to reboot to recover. OSX seems to be able to run out of RAM without getting itself in a knot--especially with the latest 10.9 release.
"Hmm, DL'd the latest...none of the apps runs, and the Python script does nothing. I'm impressed. Also impressed by the confused state of the website. Hmm."
I'm not sure if the latest is stable. I use the 4107 version from April. The Kicad devs have done a lot of revising the PCB and library file formats after that version.
Download the package and unarchive it. You'll get the resulting KiCad directory. Drag that somewhere useful, perhaps into your home directory, perhaps into /Applications (which I did).
The applications should open without issue. Start with launching the kicad program; that's the umbrella app/project manager. From there you can create new projects and from with a project you can create schematics and PCB layouts.
NB: in that archive is a directory called data. That directory includes the default libraries and templates. On OS X, the applications all prefer to see the libraries in ~/Library/Application Support/kicad, so move data to that location (rename data to kicad). In that directory, the subdirectory library holds the schematic symbols and the subdirectory modules holds the footprints.