"question: will I get a longer session before the battery dies with the firefly 2 in comparison with the firefly 1? Ive already switched to the newer 770 batteries."
The Firefly 2 purportedly allows 40-80 draws per charge, and it comes with a spare battery. One reviewer notes the original Firefly battery allows 25-30 draws. So, if these figures are reliable, the Firefly 2 should allow approximately twice as many sessions.