Has anyone been to a radio shack lately? The 17 year old kid at the counter just says, "This should work," and sends you out the door.
Wow.
I feel bad for this guy, but knowledge is power and you should be using the batteries recommended for your unit. Period.
I doubt we are going to see this incident compared to a cell phone or other hand held device. I'd hate to see what would happen should you shove the wrong size battery in your iPhone. iExplode?
As a mod owner several times over, I'm no expert in electrical engineering, but I do my utmost to keep informed. Stories like this just piss me off. I'd rather have my face intact to vape another day than save a few bux on batteries.
If you aren't going to pay attention to the safety recommendations, just f*ing smoke.