Starting the APU would also allow you to try a restart with bleed air instead of only a windmilling start (plus you'll be able to slow down from about 300 kts for a windmilling start to GD for a bleed assisted start, thus increasing your gliding range), assuming you've got altitude and time.
Also, with the RAT out powering the Emergency generator through the hydraulics, you have more than only the batteries, so are they really that critical? I was taught to always start the APU with all engines out.
Last edited by bobrun; 19th Jan 2009 at 09:31.