All components of the top mounted refrigeration system are outside of the food zone so that the full interior is usable for storage. Top mount units run cooler than bottom mounts because there is not venting problems on top of the unit. They will also keep your kitchen cooler because the warm air is kept up and out of the work area. The disadvantage to top mount units is the initial cost. However they will last longer and require fewer service calls.
Casters add portability and portability means easier cleaning and sanitizing.
We recommend you put casters on any piece of heavy equipment. Not only do they allow you to move your equipment more easily, more health departments are strongly recommending them. Casters come standard on some models and are optional on others. Stainless steel is both more durable and easier to clean than plastic. If you have limited loading space around your refrigerator or freezer, this feature could make your life a lot easier.