We have 3 freezers, two chest and one upright. I prefer the chest type because if you do have a power outage the chest freezer will stay colder a lot longer than the upright. I've gone 4-5 days easily with the chest type. Even when you open it the cold can't "run" out as in an upright. You open the door on a upright and the cold simply pours out onto the floor. We both vacuum-seal and freeze meat in water. Freezer burn is caused by air reaching the frozen product. A layer or coating of ice in a ziplock will protect meat for many years. Water (ice) does take up more space but again, when the power goes out I want as much "ice" in the freezer as possible. I also add containers of water to any odd spaces in the freezers. The more ice the better is is and it seems like our freezers don't run as long or as often to keep things frozen. And it is a source of drinking water as well.
Oh, as to cleaning out a manual defrost freezer I do it in the dead of winter when it is the coldest. A good trick is to use the larger size milk crates (box store) that are stackable. I just pull them out and set them outside when the temp is at or below freezing. Most freezers have a garden hose connection so just hook them up and run the hose outside and use a hair dryer to melt any ice. Wipe clean, turn on, and your good to go for another year or longer.
