Ok, that makes sense, but I was more concerned about the battery formulations.

Just was trying to figure out what batteries to buy depending on what you wanted. What worked, and what didn't.
Brew
One thing you didn't include is C ratings for batteries. How much current your battery can put out is important for performance.
Normal 3.7v vaping on the sparkplug is better with the AW IMR batteries because they are high drain batteries. They can put out more amps, so they heat up the atty much better. Its a difference you can notice when compared to the cheap batteries that come with the kit. The batteries stay cooler as well, and IMR batteries will last longer as long as you take care not to overdrain them.
The 17670 battery from AW is big enough to put out enough amperage to drive the atty at 3.7v as well. The AW 17670 is protected, and more user friendly because of that fact.
6v and 7.4v seem like a waste of time to me.
People talk about the superiority of passthroughs... and really I think its more about the current the passthrough can put out, rather than the voltage they are operating at.
16340 Li-ion batteries are still to small to put out enough current to drive an atomizer well.... high drain versions (which are li-mn) and good LiFePo batteries are better batteries in that size to vape off.