I tried to open some Pages files that I created when we first bought our veterinary clinic in 2008 and ran into the "too old" issue. Luckily I still have Pages '09 so I could open them. Ironically, the same version of Pages that can't open old Pages files has no problem opening .doc files from the same era.

It would be easier to work around this if there was a way to search for Pages files that will open in Pages '09 but not Mavericks' Pages. But I've examined the files with HoudahSpot and the Content Kind and Content Type don't seem to have changed. So I guess the only thing to do is look for Pages files with a modification date before some unknown cutoff.

And don't get me started on AirPort Utility 5.6 not running under Mavericks. AirPort Utility 6 won't configure older Airport Expresses, which are perfectly serviceable AirFoil destinations that I have in my bedroom, garage, and back deck. So if I need to reconfigure one I have to find a 10.8 boot disk.