Tracked down the save problem... looks like a bug in libtiff, or... an issue with FreeImage feeding libtiff the correct details. Anyhoo, a fix to the libtiff code gets tiff saving working on OS X.
Of course, since FreeImage doesn't compile under MinGW, makes it interesting to fix it for Win32...
Of course, since FreeImage doesn't compile under MinGW, makes it interesting to fix it for Win32...