To answer my own question and after a very helpful chat with them...
The 2 lb roaster can only do 2 lbs. The 1 lb version can do a "sample" roast of 1/4th of a pound. My RK drum roaster can do smaller batches, but I am looking for a roaster with a smaller footprint than my RK drum propane grill with redneck cooler does. The cooling system on my propane grill roaster setup uses a shop vac that pushes air up through a metal colander. This also helps with chaff removal AND unlike when pulling air through the beans and colander, doesn't result in melted hoses.