This is interesting to me. Prior to buying the Echo (which I recently got from Bill, and he is awesome to deal with), I had found out that my sweet spot was vaping a 2.8 Ohm carto on an 808 battery fully charged (i.e. at 4.2 volts). As I would use that battery and the actual voltage started to drop to and below 3.7 I would swap it for a fresh battery well before a full discharge so I could maintain my sweet spot.
So I bought the Echo expecting a "true" 3.7V battery that would stay near 4.2 volts a lot longer than my little standard 808 batts.
Now I have the Echo cartomizers that also happen to be about 2.8 Ohms so I should see my sweet spot at 4.2 volts again, which I now know the Echo won't do. I should be disappointed based solely on these numbers.
But I am not. The Echo is awesome at 3.6 or so volts. I don't fully understand how I am getting the same good vape with the Echo doing 2.8 Ohm/3.7 volt as I was getting before doing 2.8 Ohm/4.2 volts. I guess it must be something to do with the efficiency of the Echo cartos? Regardless, I am now happy that the Echo is apparently voltage regulated as it should mean a much flatter discharge curve.
All that being said, I still think I want to also find a "true" 3.7 volt large capacity battery with 808 threads to play with.
The Vgo is a manual 4.2 v with 808 connector but I don't find the vape to be any better than the standard Echo auto. The Echo carto doesn't fit all the way down being as the Vgo is made for using a cone like the ego so there is a little gap. 801D-1 cartos work well with it and you can use the cone with them.