Yes that's what i was getting at in some of my comments. Right now, I've observed, certain actions will force an hidden group into view. Not sure if that is a bug or a feature at this time, but probably would be a necessary feature if layers were allowed within a group/plane.
I could probably live without layers. For one thing, I could translate part of a sketch plain to get it out of the way temporarily. I've already done that on several occasions.
Now what if two shapes are constrained to each other then one of them is translated into another plain? I suppose that would just delete any constraints?