I'd recommend the switch for those of you in cold climates. The lower cutoff will allow you to run the lights longer (to warm the battery) before the battery shuts itself off.
And you guys should jump on this deal - it's a terrific (featherweight) battery, and Tony is a great guy to work with!
How many other batteries let you save well over 20lbs from stock?
Also, being able to work with battery cables while the battery is switched "off" is lifesaver. Literally!