out of curiosity shoggot why do you think that way? Thanks for the edit I am getting around the same price just figured though with 18650 there are less failure points with the dingo.
Eh, failure points? The thing is flawlessly machined - the threads won't be a failure point. Reason behind the roller vs dingo - more uniform look? The break in profile by the telescope means any minor variation in finish is imperceptible between inner tube and outer - while getting an 18650 in a dingo means three tubes joining flush, and while they join nicely, it's still a visible set of seams. So really, it's just aesthetics, I suppose?
Another way of looking at it - with the roller, there's three major threadings - bottom cap to bottom tube, bottom tube to inner tube, and inner tube to head/button. With the dingo in 18650 mode, there's bottom cap to bottom tube, bottom tube to next tube, next tube to another next tube, another next tube to head/button - so actually, more joins.
Also, when in 18350 mode, you'd have a hard time telling that a roller wasn't a dingo =) Best of both worlds, perhaps? (Note: You could totally tell, but you'd have to look for it. Height would be the same, or within 1.5mm.)