Is it possible to say ecigs are X times less harmful than analogs based on the following...
Ecigs contain 1/60th the carcinogens that analogs contain.
Ecigs' carcinogen is 1/630th the dosage of the same carcinogen in analog cigs.
Therefore...
Will anything along those lines ever produce a concrete conclusion?
No, it doesn't work like that (as DisMan has already said).
The risk of cancer is a combination of environmental, genetics and random chance. Even for analog smoking the link with [lung] cancer was proven by epidemiology, i.e., statistical analysis comparing non-smokers to smokers and adjusting for other factors.
The only way to "prove" anything with e-cigs would be to compare two groups of people (vape/non-vape) over a long period of time and compare the ratios of diseases between the two groups.