TT (or maybe it's his wife) likes dual coil cartomizers. Where is he when we need him? TT - Where are you?
Just about all I use is duel-coil cartos on my Phidias and Buzz. I use single coil cartos on everything else.
The Phidias uses 18650 batteries, 2600 mah, 3.7v.
The Buzz uses stacked 16340 batteries, 880mah, 3.6v
The eGo batteries are rated at 3.2v and the duel-coil will work on it and a lot of people use them. But this really isn't enough power for a 3.2 amp coil (each coil uses 1.6 amp) to get the full benefits of the duel coil carto. eGo does not recommend using duel coil cartos on them (from what I've read on the subject) but like I say, a lot of people do it. It will reduce the charging time as 2ndChance pointed out but it will also shorten the battery life.
I don't use the duel coils on regular 3.7V batteries either. Remember it's a DC and it needs more power to make it nearly as hot as a single coil. On just a plain 3.7V it will perform and may live for months without a problem but it will be weak. On a 3.2v battery (eGo) it will be even weaker.
Of course, all this is just my humble opinion, but I hope it helps.
TT