Just my two cents worth here. The issue with e-cigs has several facets from what I've seen. There's the FDA, Big Tobacco, pharma companies, politicians, issue groups, citizen opinions, etc to deal with.
I'd say it's similar to the gun issue. If you look at that one you may have an idea what your up against. You could have studies done ad nauseum but at the end of the day you'll still have to deal with people who won't believe the studies. You got people out there that hate guns but never touched one or had any problems with them at all. People that like guns will fight tooth and nail in every arena of politics they can. People that hate them do the same. You end up with a sort of stalemate.
Even if we get a slew of labs to say that e-cigs are ok, Big tobacco/Pharma will unleash with a slew of studies saying they aren't. Even if we get publicity out there saying e-cigs are the best thing since the wheel, you'll still have those rabid anti-smokers that won't believe it and will continue to associate them with tobacco cigarettes.
Focusing on the politicians seems to be the best way to keep them legal. Since the ECA with e-cigs is nowhere near as powerful as the NRA is to guns, we should be focusing our efforts in a more grass-roots approach.
Writing letters/email to our reps and senators and spreading the word on a person to person basis seems too slow or too much like a waste but it can have dramatic results over time. Politicians like to have issues to fight over, give em one. They hear from the anti's all the time, give em your story and they might see the potential for some sort of publicity for themselves.
Or you could always stand in front of the White House with an e-cig in your raised arm shouting "...from my cold, dead hands!!!"