I haven't heard of any issues as far as even temps on either size as long as you rotate the racks if you have a smoker full. If I have 2 or 3 racks full on my DBS, then I will rotate them at least once during a smoke. As nickcb said, it depends on how much you want to smoke at one time. Only 2 people in my house, too, and smoking jerky is the only time I fill up 4 racks. Usually only 1 (brisket, butt, turkey, etc) or 2 (ribs, fish)-and 3 racks full for cheese. The 4 rack holds more food than I thought it would.