I think that study is wrongly equating sucking with inhaling. I don't direct-inhale and I get the impression around here that few people do. I call it "inhaling", but really, I'm sucking vapor into my mouth, then inhaling it. So no matter how hard I suck on my ecig, it doesn't affect the actual inhale part of my vaping process (which is not a deep inhale in my case - I inhale lightly and exhale it very quickly, just like I used to smoke).
I'm sure we all vape a little differently, but this seems like a totally pointless study. All it's saying is that it takes more effort to get vapor from an ecig than to get smoke from a cigarette. Duh.