Kevin,

 

I misspoke earlier, the HIGH boost is used in the event of a mechanical fuel pump failure.  The Columbia has an automatic system that detects low fuel pressure and kicks on the HIGH boost automatically.  The Columbia also has a "Vapor Suppression" switch for LOW boost.

 

Like John Schroeder commented, most of us fly with dual electrical systems and a very reliable engine, that's safe enough for me too.

 

Mike