I do understand SOs, you know, and don't need evangelizing. At times, that self-containment is desirable, but in a well-managed workflow it's a big waste of disk space, and the more you use SOs the bigger the problem. What I call "Smart SO" or "Lean SO" TIFs would only consist of the link, other metadata, the updated preview/thumbnail, and whatever pixel and adjustment layers you may have added. If you screw up the link, that's your problem, and it's not rocket science to prompt the user to repair the link (eg Excel's had it for yonks, and InDesign has it). It should be an option.
John