It will fluctuate by ~-.1-.3, but not necessarily enough to ruin the vape.
The quality of a vape isn't in the numbers, it's in the puff itself. I haven't noticed vapor falloff TOO much on a low battery, but as usual, a fresh battery still gives you that extra "kick". To compensate, I usually just dial it up a little higher during the day. I use a 2.5ohm 306 atomizer, debridged and dewicked. I have yet to be disappointed with it.
I have the silver LT from Volcano with the authentic AW battery.
Before ordering though, the Trustfire charger that came with mine already started to fray on the connector cable. Volcano wants me to send it back and THEN they'll replace it. That's like a week without a vape. All my other batteries are dead and/or lost