ummmh, I thought freezer burn was caused by the exposure of the frozen food to the ambient air of the freezer, which then causes it to dry out. Thus, the frost free freezer causes more freezer burn as it creates a lower humidity environment (to get rid of the frost). We have a non-frost free freezer in the basement and the only time we have a problem with freezer burn is when I do a poor job of wrapping and sealing things before they go into the freezer. The trick I think is to be sure it is air tight before you freeze and then no freezer burn, especially for longer term storage.

As to model choice, I agree that frost free is better, but we have not found our non-frost free to be a big problem. Very little frost accumulates as we open it only occasionally to transfer items to the fridge in the kitchen.

Hope this helps.