I've made some pretty substantial changes to the alpha sheets behind the scenes, and to the Pathfinder [Legacy] sheet in particular. Please try clearing your browser cache, or post in the Experimental Features forum if there are any issues!
At this point, we highly recommend that all new Pathfinder sheets be created in the alpha and that existing Pathfinder sheets be copied into it via the 'Copy to Sheets Alpha' link in your regular sheet list
I never get hard drives to last that long and my computer desk is a mess of external drives that I try to use as back-ups and then forget to back up. The site Odin suggested looks does look very useful.