I think that you would have more choices on cartos, attys,
tanks etc if you went with a regualr eGo.(except for dual
coils and anything under 1.8-2 ohms)they work but can kill either the battery itself or the mosfet switch. I've been using my eGo batteries (have) 3 for about two months now and love them. another option would be a basic 3.7 box mod- you can charge the batteries seperatly with the correct charger and actually save some money in the long run.
Hope this helps-i'm pretty new to this myself, but have learned the hard way about ohms,resistance etc.