I don't recognize any of his symptoms anyway, and my OS X computers get pretty RAM-heavy use, with almost always a linux VM open, XCode, Safari with ~10 tabs, iTunes with a few thousand songs, etc.
I think you missed a key ingredient to this problem, which is heavy disk reads caused by either spotlight or time machine.
Reading a massive amount of data (that you'll probably not use again anytime soon) has the unfortunate side effect of polluting the disk cache with junk. Now if OSX is anything like Linux in this regard, it is loathe to toss out old disk cache (in response to all the incoming junk it's being asked to cache) and will instead start swapping to free up more memory for disk cache.
Linux has /proc/sys/vm/swappiness to control how aggressive it will be in swapping stuff out to preserve precious buffer cache, but I don't think OSX has any such mechanism.
I think you missed a key ingredient to this problem, which is heavy disk reads caused by either spotlight or time machine.
Reading a massive amount of data (that you'll probably not use again anytime soon) has the unfortunate side effect of polluting the disk cache with junk. Now if OSX is anything like Linux in this regard, it is loathe to toss out old disk cache (in response to all the incoming junk it's being asked to cache) and will instead start swapping to free up more memory for disk cache.
Linux has /proc/sys/vm/swappiness to control how aggressive it will be in swapping stuff out to preserve precious buffer cache, but I don't think OSX has any such mechanism.