You are correct that the paddle tube reactor may have a lower...

You are correct that the paddle tube reactor may have a lower output for its size, but it is more about flexibility than output alone
A FBR requires a gas flow range to give the bed its fluidised character and does not have much of a range in which it can achieve this, you need to size it to the output in design stage. (Hazers current reactor is only 75mm internal diameter from memory)
Whilst a paddle tube is mechanically mixed on a variable speed. The advantage being the ability to vary the mixing/contact ratio independently, so they can experiment with paddle speed and gas rate as separate parameters.
When you breakdown the ~3kg/day rate, its only ~125 g/hr, and powdered graphite is heavy at 2.25 kg/liter, so only ~56ml/hr of powder.
Its a very large reactor for 11 teaspoons an hour