Hello. I've been researching the echo for the past week or so and I might be of at least a little help to ya lol. As I understand it about the only difference between the ego and echo-e is the echo-e comes with and echo-e cartomizer. And if I understand right the echo-e
batteries aren't regulated down to 3.3-3.2 ish like the ego batts are. And the echo-e cartomizers are 510 compatible so it would work on your ego or (almost) any 510 connection. I hope this helps and is accurate and I'm sure someone with more knowledge than I will be around soon enough to help you more than I can.