@James, with the solid copper 510 tool, with multiple 200's using the last 2016/02/23 firmware and escribe 1.0.39 or 42, I was getting down to .002 on a couple mods. Later firmware and escribe was down to ~.006 before a ? mark. The last i checked (if you can tell I'm a mod res natzi) it would get to .005 and stay there, but testing on the prior versions would still get my 11 DNAs .002 and higher. The 75 non color (when tested) managed to show lower values. You said "Always make sure the Mod Resistance you have is conservative", they (users and quality manufacturer's) will think .005 is accurate.
I don't own a C version.
On my BilletBox (only DNA60) it was set at .0004, and no way to validate that or thermal characteristics (even though I only need board temp to room temp offset) as there's no USB port. Telling me another way is more useful, than an easy 'just use the defaults'.
I had a DNA250 custom built, with the shortest, biggest, fattest wires possible for every connection with a shitty Varitube v2 (which is now being replaced) and got .003 using an alternative method.
I'm no Electrical Engineer, but if a '0' value is the default, couldn't you put Mod Res calculation on the Manufacturer Mod tab, and perhaps disable the fire button, allowing us to use the solid copper tool or something? A simple yes or no would suffice. A nice feature would also allow one to Save "Mod" parameters, allowing us to load default settings across the slew, then load individual Mod parameters.
Mod Res setting IMHO is a 'premium feature' parameter from the Temperature vaping pioneer company.