Problems with the MVP:
Lithium battery is more dangerous [and more expensive and more difficult to procure] than other types.
Battery is not replaceable. When it goes kaput the entire device must be replaced even though all other parts might be in good condition.
Too expensive up front and over the long haul.
For those living in one-horse towns with no vape shops local, procuring the device is a hassle.
Instead of carrying a cellphone with a battery and an ecig with a battery, a more elegant solution would be to carry a separate, universal battery module (UBM) to which a cellphone module (CPM) and an ecig module (ECM) could be attached.
The UBM would contain replaceable, relatively safe, rechargeable batteries, and could be stacked (serial and parallel) to increase capacity. A conventional charging module (CCM) and solar charging module (SCM) could be carried or left at home, as desired.
The UBM would not be limited to just powering the CPM and ECM. Since UBMs are stackable, the sky is the limit. I can imagine other modules.