I believe that the 2 ohm dc's are meant for higher voltages and won't work very well on an ego batt. I've never tried them though. Those ones are smoktech.
Edited to add: I heard that Boge will be bringing out a 45mm carto next month so you may not have to cut down your tank.
So in general, dual coils just aren't that good for ego's? If 1.5ohm is too heavy a load, and 2 or 3 ohm carts are pretty much for high voltage batteries, it doesn't sound like there is any good dual coil solution for the ego's.
I do however have a ego mega dual coil cart (5ml) on my ego right now (from smoktech I believe). It does feel a touch underpowered, but it works very nicely actually. I'm running out of power faster though. These are made for the ego, and are listed as such with specific ego threading, so I figured it's at least pretty safe.
I also have an echo-e dual coil from mountain vapor, also made especially for the ego. It feels even more underpowered, producing a little less heat and vapor than the EMDCC. So far, the EMDCC is one of my favorite carts, cause you can literally "dump" liquid into it, it's just so dang big!! Almost too big (from a visual standpoint, including mouthpiece, it's about as long as an ego 900mah battery!). On the ego, it looks like a bloated big brother of the cigeasy elite 808..LOL