@ "That said, your boil time for 3 cups beats most alchy stoves' 2 cup performance!"
Yes, the TIME beat most other stoves. But how much fuel was consumed? Because that's how you get an alky stove to beat a canister stove on weight- you need decent fuel efficiency. With that quick a boil time I'll almost guarantee that he burned a ton of fuel.
I've done a fair bit of comparison recently, and that seems to be the trade-off: Faster boil times consume more fuel. He needs to fiddle with letting more or less air get through the windscreen, and the height of the pot above the stove, and see which nets the efficiency/time tradeoff that he prefers.
Clearly, though, yes, the low-hanging fruit right now is a wider pot. Or, actually, maybe a taller windscreen- in the house that tall jet of flame up the side of the pot probably worked well, but in even the slightest breeze it won't. Also, I have to wonder if those flames burn so high because of all the air they're getting? Maybe a higher windscreen would lead to the stove burning leaner, and thus a longer boil time but better efficiency.
Do you have a scale? The easiest way to measure fuel usage is to weight the filled stove before boiling, and snuff it and weight it afterwards and do a little subtraction.