Are we talking about the dual coil cartomizers with the hole in the side and big tank on the outside? If so we are also looking into one of these with a big battery mod.
I have a couple of prototypes from manufacturers on my desk right now, and one looks to be working pretty well. Putting it through the paces for a few days to see if there are signs of leaking, so far none. The other would be awesome but it suffers from leaking right away but I see the issue and hope to have them fix it. It is a variable voltage that takes 2 3.7v 700mah batteries. It varies from 4 - 4.5 - 5v at the press of a button.
Hopefully we can get these things working right