I am pretty darn sure these things are specifically designed for people using 3.7v devices. With exception to the Provari, Precious, or Darwin, 99% of people are either vaping at 3.7, 5, 6, or 7.4 volts specifically because those are the only choices. I would even be willing to guess that most people are probably still vaping at 3.7 volts.
Lower resistance atties/cartos are specifically designed for people vaping at 3.7 volts to allow people to get the 'effect' of higher voltages without having to buy a bigger / more expensive mod.
These things in fact work 'really' well with a simple Evo battery.
In regards to Amps, I find it hard to believe that anyone is using a battery that cant push at least 1.5 amps these days. I suppose if you are using an original 901 or 510 titan, maybe but I would say those people probably arent vaping on dual coil cartos either. These are devices that extend outside the scope of people still using noob/starter kits. I think most people looking for lower resistance atties have a 'decent' mod or at least an Evo battery (which pushes out just under 2 amps).
And Im sorry, I contest the notion that dual coils are the same as a single coil at half the resistance (ie a 3 ohm single coil does NOT equal a 1.5 ohm dual coil). That is the part that I cannot exactly explain the science or math of. I know how dual coils work, I know the math behind them and on paper, a dual coil is the same as a single coil, if they both have the same resistance - ie a 1.5 ohm single coil vs a 1.5 ohm dual coil. They perform differently but how exactly (other than more 'coverage' in the container) I cant give the science or math (logical reasoning) for.
I am sure of the science involved and work with it every day. 
