I really think for a dribble pour the balance on the thumb technique is easier to manipulate - no idea if this was the intention of the design but it seems easier to make small adjustments to the stream flow by rotating my wrist rather than lifting my elbow and turning my wrist down like I do when pouring from my Aroma AWK kettle - of course with the Aroma speedy pouring is the name of the game - more like a paint roller compared to the artist's brush that is the Bonavita spout.
