Not sure what to say about what others might have said/believed, but I've never held it, or similar vapes, to be anything but conduction. Since before I knew about vapes. Since school and all that Thermodynamics stuff. Made a living following those rules, I believe in them.
OF
Everything you said is true, assuming you made valid assumptions to being with. That being said, I don't know what the actual temp of the "heating element" is at the time of use. What exactly are you measuring when you assume the F2 is only generating 400 degrees at its "central core"?
I seem to remember a similar discussion about the now-defunct Haze Square (which I also own). It was a "true convection" vape that heats by air passing over a super-heated exposed coil. My main reason for buying one was so I could just take a hit or two and leave the rest for later - an "on demand" vape with a 3 sec heat up time. But the question of "what temp is it at" was one hashed out a few times. The conclusion was that the "temp setting" was really an estimated vape temp because the coil was generating MUCH higher temps (like 900+ degrees). This is consistent with your thermo analysis.
So the real question is - how high is the actual core heat temp when you set the (estimated) vaping temp on the F2? It probably is similar to the Haze - MUCH higher than 400 degrees. When you set your F2 at 400 degrees, you are not setting the heater to 400 degrees. You are setting the heater to a temp that produces 400 degrees of hot air. For all we know, the F2's core is heating to twice that.
This would explain why the F2 functions as a true convection vape, although NOT an "on demand" convection vape since it needs to heat up for 20 secs. (What is the limit on using the "on demand" term anyway? 2 seconds? 10 seconds? zero seconds?)
The F2 vaping experience and ABV also acts like convection and not conduction. I've own a few portable conduction vapes, and my current goto is a Haze Dual. Conduction vapes all seem to product a much darker ABV, and although some are more consistent than others, ABV has a few darker areas where the material makes direct contact with the metal bowl. However, all of the ABV I've observed from the F2 has been lightly brown and very consistent. In fact, the ABV is identical to every other convection vape I've used, including the Square and Ghost.
The vapor itself is like a convection vape as well. It's lighter, tastier, but mostly, you have to work a bit to get vapor. My Haze will start and finish a bowl without me ever taking a draw because the material is in a hot oven. It doesn't need a draw to work. The F2, however, does seem to need a draw. In fact, just like the Square, it needs a good healthy draw to work at all because it's not being heated by an oven, but by the air you draw over it. At least that's how it appears to me.
So I just did a pod test. Put in a freshly filled pod, turned it on to 420 degrees, and let it timeout without a draw. Looking at the material, it's a bit tanner looking, but not dried. So I then attempted to vape that same pod, and it vaped great! I got the same hits as normal (about 4-5 good ones) and it tasted right too. If I did that in any my Haze Dual, there would be nothing left to vape.
So call it whatever you want, convection or hybrid, the metal bowl is certainly not heating to 420 degrees. If it did , it would vape all on it's own. It needs the hot air to work - like a convection vape.
