A mechanical mod's advantage is that it will fire all attys no matter the resistance, that's why RBAs and gennies are highly favored to put at mechanicals, because these attys work best near or below 1ohm. Now for example, i run my 0.8ohm did clone on a mechanical with a battery fully charged, that's approximately 4.2 volts of power put to the did. that's about 16+ watts (idk the math) wherein a regulated mod like a Provari wouldn't let you go that high, and 1.2ohms and below on a provari would not fire.
But now you might be thinking, what would be the difference if you use a 2.5ohm atty and fire it at a certain voltage to achieve the same watts? Well, it would taste burnt, but on a 0.8ohm coil at 4 volts won't. That's because sub ohm coils in RBAs use a lower gauge of wire which is noticeably thicker, meaning it has a higher resistance of temperature, that's why it won't taste burnt. But a higher gauge wire in a higher ohm is very thin, that's why it will easily get hot and will be the source of burn tastes.
Now about the voltage drops on mechanicals, this is the problem for those. Voltage drop on mechanicals are unavoidable unless you use a drop in regulated module like the Kick, but the Kick will only go as high as 10 watts, so it's not preferred for RBAs. Voltage drops will be less if conductivity were to be improved by upgrading the pins on the mod itself. I don't really know what pins are on many mechanicals, but an expensive or a high end one will atleast have copper pins. positive and negative pins made of copper will highly improve conductivity, thus minimizing the drop. But there are also silver pins, which are considered to be the most conductive metal on earth. I don't know if someone upgardes pins on the US, but here locally i know a guy who does.
Hope this helps!
