Hi Matt,
Size does matter, a lot, the upside is the ease and reliability of the system with good fuel prep.
I get my best results with a spread between 3 and 12 mm (1/8 to 1/2")
Sieving that is a piece of cake.
The gas temperature stay’s low, the gasifier relative cool , gas stay’s dry.
When you overdue the waterdrip, then your charcoal becomes moist and a pain to restart next day.
I adjust waterdrip according to my load needed, with a baseline 1 drop per sec, (20 drops equals 1 ml ) = 0.18 liter/Hr for each Kg of charcoal consuming.
The max i went up to this date = 1 liter /Hr per Kg charcoal, but then i am running the engine at max and use the exhaust wall surface to turn the water into steam before injecting that into the gasifier
I tend to run the level of the charcoal bed not lower then 24" above nozzle, that certainly helps ,in my case, to have good power output.