NY wrote
Rod Speed wrote

A consequence of frost free is it dries its food contents.

Bull****, mine doesnt.

Yes, why should frost-free (periodic heating of the cooling element to
melt any ice that has formed on it)

Thats cyclic defrost, not frost free. Frost free passes external
air over the cold plates outside the freezer or fridge, and gets
any moisture in the air out of the air and pumps cold air into
the freezer or fridge. There is no cold plate or coil inside the
fridge or freezer.

make freezer burn any more or less likely?

In fact it makes it impossible because there is no cold plate
or coil inside the freezer. Thats what produces freezer burn,
the surface moisture on the food subliming from the food
surface to the cold plate or coil.

Isn't freezer burn dependent on how much (if any) moisture gets in from
the outside,

No, thats frost, not freezer burn.

and therefore on how good the door seal is? And on how often you open the
door, letting in fresh, moist air from the room.

One of our freezers uses about 50 W when the motor is running (and near
enough zero when it's not), but every few days there is a sudden burst
when about 700 W is used for a couple of minutes. I presume that's when
frost-free has kicked in to melt any ice on the cooling element.

Thats actually the cyclic defrost.

It's amazing what you can tell from a smartplug that reports power
consumption every few seconds, to be logged and graphed by a suitable
utility on a PC.

Yeah, very useful tool now and dirt cheap too.