[bdery]

Hilariously, the power in the specs table at the back of the V1 manual is given as 76Ws, not a guide number at all.

Well, Watts are a measure of power, whereas GN is a measure of range. So giving a flash power in Watts makes a lot of sense.

It's also the norm for powerful off-camera strobes.

I put much more value in Watts than GN, for the reasons mentioned above. When flashes are spec'ed in Watts, they can easily be compared regardless of the position of the Fresnel lens.

[inkista]

Well, Watts are a measure of power, whereas GN is a measure of range. So giving a flash power in Watts makes a lot of sense.

It's also the norm for powerful off-camera strobes.

(Nitpick). It's not Watts. It's Watt-seconds (also known as a joule). Different unit. Ws/Joules/Wh measure energy; Watts measure power (rate of energy exchange). It's not like rating lightbulbs at how much power they can safely take (like with LEDs). It's the measurement of energy used.

And Watt-seconds can be as bad as guide-numbers on determining how much light is put out, because it's only a measurement of the energy consumed by the device. A less efficient bulb/circuit means less light (more heat) for the same energy consumption. It's how Godox lights that nominally have higher Ws ratings than similar Paul Buff offerings might actually put out less light.

I put much more value in Watts than GN, for the reasons mentioned above. When flashes are spec'ed in Watts, they can easily be compared regardless of the position of the Fresnel lens.

Except. The light you get changes, regardless of the watt-second rating, depending on whether you're using a reflector or not, what modifier you might be using, how the bulb is positioned in the modifier, etc. etc. Also a bunch of other variances, and while possibly not as opaque as guide numbers with their sliding zoom factors, still can be inexact for apples-to-apples comparison.

There are reasons you'll mostly see tested comparisons between lights and different types of lights done with light meter readings, instead.

We also still need a good way to quantify light output from strobes to continuous lights, like say, LED CoB video lights. I'd probably be happiest with lux at full power over a standard distance/reflector/modifier setup, but I'm weird.

[bdery]

(Nitpick). It's not Watts. It's Watt-seconds (also known as a joule). Different unit. Ws/Joules/Wh measure energy; Watts measure power (rate of energy exchange). It's not like rating lightbulbs at how much power they can safely take (like with LEDs). It's the measurement of energy used.

We're saying the same thing, basically. As we both wrote, Watts measure power, which are Joules/second. Thinking about it, however, I'm probably more interested in how much energy is delivered per pulse, which can then be modified by the zoom setting, modifiers in front of the flash, etc. But that wouldn't work very well for continuous lighting, where power would be more relevant.

We also still need a good way to quantify light output from strobes to continuous lights, like say, LED CoB video lights. I'd probably be happiest with lux at full power over a standard distance/reflector/modifier setup, but I'm weird.

I would rather have info about the total energy. In any case, zoom settings aren't important when you bounce or shoot through a modifier (umbrella, softbox, etc).