Duals are generally going to perform better. Let's not get into solipsism over the true definition of "better." The difference in performance is easy to understand without splitting hairs.
A dual coil gives you double the power and surface area of a single. If we are to assume that flavor, vapor production, and juice consumption are the main parameters for gauging performance, then adding a second coil of the same mass/resistance to a build is going to improve performance drastically. You are vaporizing twice as much juice at the same rate. Personal preference has nothing to do with the fact that it is serving its function more effectively in an objectively-quantifiable sense. I'm talking about a measurable difference in the quantity of juice being vaporized, which is hard to argue does not directly translate to an increase in flavor.
What I think you're missing here is that you need to add a proportionate amount of power to the increase in mass. With a mech, the only way to do this is to build your duals at a lower resistance than you would a single.
A .5 24g single may heat up fine, but when you're distributing the current across two paths, you need much more of it to attain the same heating properties. The individual coils in a .5 dual setup would have a resistance of 1 ohm each and thus pull the current of a 1 ohm coil, not that of the combined .5. Not only is either coil alone double the size of the .5 single, but they each pull half of the power.
So whereas you have 8.4 amps going to a .5 single, you only have 4.2 amps going into either coil in a .5 dual. They pull a combined 8.4 amps. The same wattage that powers one coil cannot adequately power something with double the mass. A .5 single generates 35-odd watts. A .5 dual also generates 35-odd watts, but each coil is actually only generating 17.5 watts.
If you want more flavor than a single .5 24g, then you should do a dual .22-.25 24g. Try a dual 24g, 6-wrap, 2.5mm build and see for yourself the difference that it makes.
You can even get something with comparable flavor, but more oomf at .2, which is 5 wraps instead of 6.
The same would apply for a dual 26g, but you'd want to keep it in the range of .3-.35. Since the wire is thinner, it not only pulls less power for each unit of mass, but requires less power to heat up. Mass-wise, it will be roughly the same as the dual 24g I just mentioned. All that will change is the ramp-up and overall temperature. Flavor would be similar, but the vape itself will be cooler. It heats up faster, but pulls less power to do so and retains less heat.
Twisted 26 is going to kill both of those in flavor. It has more mass than 24g and twisting wire gives it unique wicking characteristics which further improve flavor. A dual .2-.26 would be lovely on your tube mod. You could also do a dual parallel 26 at .2 for a smoother, but no less flavorful vape.
Hopefully that helps you grasp the bigger picture behind duals. I noticed you've asked about them before, so I went into a bit more detail than I would have otherwise.
Guess he hates everyone.
