In Adobe Camera Raw, I know of 3 options for opening files in Photoshop:
If you click the
Open Imagebutton, it saves your changes to a sidecar xmp file (or database if you've set it up that way) and opens as a raster image in Photoshop.
If you hold Alt and click the (now)
Open Copybutton, it only opens as a raster image
If you hold Shift and click the (now)
Open Objectbutton, it saves your changes to a xmp file and opens as a smart object in Photoshop
Is there no way to "Open Object as Copy", i.e., open as a smart object without saving the changes to a xmp file?