I've got a Glow '21 with the stock cover (yellow).
In comparison to my current reader, an Onyx Poke5, the Glow is a big, fat cow.
Ok, I made a bunch of mods to my Poke5 for which I am very happy.
Described
here.
In any case (so to speak) I will never install a magnetically attached cover or a full (front & back) cover on any future device.
I want to protect the front but I don't mind if the back of the device gets scuffed.
In the future, I will either make or buy a front flap (with auto sleep) and a vestigial back side.
That's another thing that drove me from B&N, no auto sleep???