Pro: A little more streamlined by eliminating one hose, and donating the reg you know works (primary) to take care of the emergency first.
Con: Primary inflation is same source as backup gas source. Also donating primary short hose almost requires vertical ascent making venting BC from rear dump nearly impossible unless you and buddy are properly trained to do horizontal ascents.
Con: Primary inflation is same source as backup gas source. Also donating primary short hose almost requires vertical ascent making venting BC from rear dump nearly impossible unless you and buddy are properly trained to do horizontal ascents.