If you really want a recommendation on batts i would suggest
mods using 3.7v batts.. Any
mods, DIY or ready made doesnt matter.
oh wait, it didnt occur to me just now but it depends on your Ohms of the dual carts too. If you use normal resistance cartos its still fine with ego batts. Just take note that with Ego batts, using LR cartos and atties will overtime reduce your battery capacity until kaput. I had a few died on me within a few weeks last time just by using LR atties exclusively.
Unless your talking abt 900mah V.E.T its the same output at around 3.4v.