"That is what is good about the titanium version caldera. If you have firewood, you burn it. If firewood isn't present or isn't legal, you burn alcohol in the little alcohol burner. If you have run out of alcohol, you use the backup Esbit burner."
No argument about the flexibility, it would be very nice to have. I'm just suggesting that for a thru-hiker on the PCT that it might not be worth the weight penalty.
Don't get me wrong, here, I can easily see someone coming to the opposite conclusion; not having to carry fuel would certainly offset that weight penalty. If, again, it's worth it to you to deal with the "little fire" aspect and to figure out where it's okay to do that (for much of CA, I suspect maybe not ...).
W.r.t. size of pot: even when eating quite a lot, with the freezer bag cooking approach, an 850 ml titanium mug does me fine. 850 ml is 28.7 oz or about 3-1/2 cups. I can't remember ever eating a meal where I needed to add 3 cups of water to rehydrate it.
Certainly the answer could be different for someone that is inclined to cook in (and then later clean) the pot.