Initial Mac set-up is described in §5.4 below.
In the summer of 2012 I was forced to upgrade from Snow Leopard to Mountain Lion in order to run an Xcode version > 4.2 which is required to compile code for present-day iPhones and iPads. (Yes, it appears to be impossible to create an iPhone/iPad application using Snow Leopard.) The initial install (7/25/2012) went smoothly, although I was surprised that some of my personal settings were lost (which were easily re-entered). Overall, the experience has been a regression for me since many MacPorts ports do not compile on Mountain Lion as of this writing, UI changes are in a sideways direction for me, and so far I have not identified a single new feature that I care about. One annoying new development was that for several days I could essentially never eject my external hard drive (cleanly) without powering down (even after disabling Spotlight, which I believe to be the source of the problem). More significantly, I am experiencing a decline in general performance (responsiveness of apps, especially within VMware Fusion), even though I have 8GB of memory that is not being filled, according to Activity Monitor. Perhaps my old dual-core MacBook Pro is underpowered for this OS. Unfortunately, upgrading to a new MacBook Pro would mean losing a quarter of my disk space, since they don't offer a 1TB disk option, and one can no longer upgrade disks later. (I hear the memory and disk drives are now permanently mounted on the logic board so they cannot be upgraded.)
So, I'm in the common situation of having upgraded software to the point that a hardware upgrade is also needed, but there is no way I can do that (presently) without regression in disk space. My old Mac Pro is even more long in the tooth, and I've found no obvious upgrade path for it at all, so I plan to abandon that line and stick to Linux for desktop computing.
In my opinion, Apple is not providing nearly enough hardware-upgrade support for its computers. They are great if you treat them as disposable, but that seems like a waste. Maybe there are reliable upgrade alternatives I haven't yet discovered.
I would like to try out life on a maxed-out Lenovo Linux laptop. My main question is whether I can get all my Windows stuff running under wine (which I can pursue in advance on a Linux desktop). For Xcode, I'll have to keep using my old MacBook Pro, which isn't so bad. It is the performance of Eudora/Windows under VMware Fusion 4.1 that I find intolerable (frequent very long pauses). [This issue was resolved in VMware Fusion 5, so as of summer 2013 the performance is great.]