We already know that using appropriate gears and nicotine load in our ejuices is critical for successful switching, from analogs to vapor. I first failed with the blu sticks and an Ego-u loaded with basic tank containing 24mg/ml ejuice. I found this freshly published paper @http://www.ncbi.nlm.nih.gov/pubmed/26377515, which put some numbers into it: Effects of Electronic Cigarette Liquid Nicotine Concentration on Plasma Nicotine and Puff Topography in Tobacco Cigarette Smokers: A Preliminary Report. I cannot get the full text, but the the abstract worth the reading. Nothing really astonishing but yet this study implies that ".... the nicotine delivery profile of a 3.3V ECIG with a dual coil, 1.5-Ohm cartomizer approaches that of a combustible tobacco cigarette in this population. Finding a product that delivers nicotine as effectively as a tobacco cigarette, as we report here, may be essential for smokers who want to replace completely their combustible tobacco cigarettes with ECIGs."