Can you help me understand what 'Update Existing Layer' does?

Scott wrote: When updating a layer, are we moving file and / or registry information from the Read-Write Sublayer to the Read-Only Sublayer?

Here's the skinny, Scott. Update Existing Layer doesn't move anything. It simply re-enters capture mode, so that anything you do while the animated lightning bolt is in the system tray gets written to the read-only sublayer.

That sort of merge you describe, of the writeable sublayer into the read-only sublayer would be new functionality. It doesn’t exist yet. But, stay tuned, a "Layer Press" tool will be posted to the Juice in a month or so that does this!