As far as nicotine consumption is concerned, the amount your body gets over the course of the day is the same because you will vape as much as required.. your body will adapt to the new method and basically crave more or less vapour until there is an equalibrium etc..
The primary ingredient PG or VG have proven themselves to be healthier than smoke.. it's all the little secondary and tertiary chemicals that haven't had enough testing to know for sure. Pick up a bottle of LF and you will see all of those extra chemicals. The big tobacco companies say that if something is ok to "eat" then it is ok to smoke.. at least this is the simplistic way of putting their argument. Brown sugar for example is a common ingredient in many brands of cigarette. Burn that stuff and ihale the smoke sometime and you will definitely be doing damage to yourself. How all these flavours and chemicals in minute amounts change their chemical structure when converted into vapour is the only real concern I have.
Having said all this however, even if vaping was 10% healthier.. I would still be urging people to vape instead of smoke. It doesn't take years of study and a rocket scientist to know that vaping is, at the very least, marginally if not profoundly healthier than smoking. Is it "better"? That is a question for the philosophers of the world..