Good question. Considering this myself. More for the battery life than anything else. I really like my Dura C (510) i think the vapor production from it is fine. My only complaint is that the vapor drops as the batter life drops.

So more battery longer vapor. I'm going through about 5 battery charges a day on the 510. I just rotate off charging one and using one, but that means pacing myself for the several hours it takes to charge one. And carrying my charger to work

. Anyway would love anyone's personal experience who upgraded to the ego.