layer retentive splicing would be good.
I could select a folder or group of layers from the layers panel, right click and say 'load to new PSD', which would simply make a new PSD of all these layers only.
Easier than opening a new document and dragging the layers over.
That is almost exactly the same, but I think what I was suggesting (rather unclearly) was an option for the stage size to be that of the duplicated items. At the moment clicking 'NEW' keeps the same stage size, but would be nice if there was an option for the new file to be only the same width and height as the duplicated items.