Actually you don't have to calculate anything. Start with your voltage setting low and increase it till you're happy. You are done. No worries about misreading the atty or the device going crazy. When I use VW, I still seem to have to adjust wattage when I switch atty's. Cheers
Your reasoning is flawed. Using VV or VW you can similarly start at a low setting and increase it until it vapes the way you want. You don't HAVE to calculate watts. You can treat it like Zen's arbitrary 1-10 scale except in the case of the Radius it is an arbitrary 1-40 scale.
Although you are technically correct in that different atty's will deliver a somewhat different vape with the same wattage setting, it can be easily demonstrated that wattage is a far superior proxy for what you look for in a vape, as opposed to volts. Watts equals power and for the most part the same power applied to a coil generates the same amount of heat and approximately the same amount of vapor, to the extent that different atty's can be said to behave similarly.
The biggest variance among atty behavior as a function of watts (power) is probably the number of coils. If you vape a single coil atty at 10 watts and then change to a dual coil atty at 10 watts, you have reduced the power applied to each coil to 5 watts and that will substantially change the vape. But the controlling variable is still watts- across each coil.
Volts has no predictive value whatsoever (unless coil resistance is unchanged). Put 5 volts across a 2 ohm coil and it will behave totally differently than 5 volts across a .3 ohm coil. The 2 ohm coil will deliver 12.5 watts, the 0.3 ohm coil 83 watts!
Put another way.... if you hand me an atty without telling me the resistance I can have no idea whatsoever where to set a starting voltage (other than "really low just to be safe"). However, if you tell me how many coils it has, then I can decide a reasonable starting value in terms of watts per coil. I will probably have to tweak it to preference based on the characteristics of that atty and coil build, but I know that 10 watts (for example) will get me very close to what I like. And it should not burn out the coil, for example, or make the vape "go crazy". If I put 5 volts across an unknown coil, it may go crazy (it could try to fire at 83 watts per my prior example!).
The people that insist on VV are probably either using only a single coil resistance, or a very limited selection, and they have dialed in their preferences for the resistances they use. They could do the same with Zen's 0-10 scale, and it has just about as much meaning in the broad scheme of things. They are also not pushing their VV Provaris and are not running into constant over limit errors as they adjust coil resistance and try to find the voltage boundary that results in whatever wattage their particular sample allows (and I understand that varies from sample to sample). Nor are they using a calculator to back into volts and then back further into the 14W (or whatever it really is) limit. Personally once I got a VW device I never looked back. If only for that reason. And since I build my own coils and have a lot of atty's I have a wide spread of resistances to deal with.
Although I think Provape did the right thing from an engineering viewpoint, I think it was a poor decision from a marketing viewpoint. That because no matter how much logic and reasoning and ohms law is thrown at this debate, a certain number of people here will not buy a Radius without VV. Even if VV makes no sense as a preferred setting strategy from a technical viewpoint. As a software developer I learned that lesson at least 20 years ago- being technically correct is rather meaningless in the world of commerce. On the other hand, it is very obvious to me that Provape is a 99% engineering driven company, and about 1% marketing driven. And that is what makes them different. They would not be what they are if they were marketing driven. They would be like every other mod company, selling 200 watt box mods for $50 or less.
