e-cigs, regulation, and substitution effects

Here's a seemingly-thorough Heartland report on a topic I haven't followed closely-- but an interesting topic for a number of reasons: 

1.) E-cigs aren't a healthy choice, but they seem to be (far) healthier than cigs.
2.) E-cigs could be a gateway to cigs-- or away from cigs.
3.) E-cigs are a substitute for cigs, so more regs (and increasing the price) could prevent more people from smoking AND/OR prevent more people from substituting from cigs to e-cigs. 

So, what regs should be put onto e-Cigs? Of course, there are philosophical and practical issues here. Sticking to the practical, what would regs do? It depends on the extent of the above factors.

What should Big Tobacco want? If the "gateway to" factor is strong, e-Cigs could be a net gain. If e-cigs are a strong substitute, they would want e-Cigs to be regulated to make them less attractive. If e-Cigs are a gateway out of cigs, that's a big problem for cigs-- and makes regulation even more attractive. In these latter two cases, the only other factor is cigs reacting to an overall reg environment: if e-cigs are regulated more harshly, then there may be spillover effect for cig regs. 

Here's a MI essay by Charles Hughes (including a claim by Grover Norquist that ecigs may have tilted the presidential election!) and an AEI piece by Dr. Sally Satel, responding to a NYT piece.