The bowl is a cooling tray. Size is irrelevant....a bigger cooling tray just means the roaster can roast more coffee.
If you want to talk quality of the roaster, brands such as Yucel are basically your Hyundai roasters as an analogy. Some of the big boys of the roasting world are Brambati....their smallest roaster is 120 kg....all cast iron drum and made to order....unlike Yucel which has a stainless drum. The best roasters have cast iron which has the ability to retain heat and doesnt get affected as badly by draughts through the building.