they are not all the same size tho..
part of the design parameters behind the SD was to keep it as small as possible whilst at the same time contain an adequate sized battery..
in short a compromise between battery run time.. battery life time and ergonomics.. this was nine months ago... back then the SD was huge compared to the average sized e cig.. we did start a new thing..
trog, your long post (very informational, thanks) only reinforces my initial thought that the OP needs to define what it is he/she wants in a device and then find the device that best fits the needs. It could be battery life, throat hit, type of atomizer; we do not know.