Lacey, I can agree with you on the most of the points that you're making, like that manufacturers have 300 puffs number to describe the cartridge, and that surveyed customers take about 63 puffs per day.
Where Kate and others have problem with is that puffs are far away from accurate measurement to support any comparison. E.g. I can take 1 second or 5 second puff, and the difference on the liquid/cartridge usage per puff would be huge. Up to the point that the true study can show completely opposite numbers. I am not saying that it will, I am saying that it could.
To conclude anything about nicotine consumption for ecig consumers, we would have to at minimum, ask consumers if they are completely replacing their smoking, and how many cartridges / how much liquid are they using. This would be inaccurate as well, but much less, and inaccuracies would go against our point, which can only contribute to our stand (basic rule of the debate). Just look at how difficult it is to debate that issue with Kate, who's pretty much on your side here, now imagine zealots like ash. If their study finds 10% more usage than yours, they are in the clear win of that debate point, independent of the fact that 10% doesn't mean much. Order of magnitude difference, which is quite possible mind you, can win the whole debate if it leads to suspecting the rest of our findings.
Personally, I would leave the whole nicotine story outside of the debate. There is no proof that nicotine causes any problems when below toxic level. Let's try focusing on effects on the environment, positive reactions from smokers who switched, etc.