great way to explain the differences Rob; I can see myself quoting that some day.
Personally zooskifilms; I feel LR would do that so easy; or should do that so easy. I feel the frustrates; especially those using LR for work. That is the beauty of lightroom; it's easy to add the same edits to the following image or to lots of files with 'auto sync'. I still don't understand why I had lots of drama like you and now don't have so many. To those 200 files I mentioned earlier I auto synced lens correcting/sharpening and noise reduce plus some basic editing without any dramas. But I do wonder if I could have done that when I was having similar dramas to you.
Just did an experiment: took a file and basically destroyed it by moving every slider and using every tool available several times>>added those edits to 56 lumix raw files with sync>>took several minutes>>selected one of the files and removed those edits and re-edited the file in a way it would be destroyed if done in PS and all with no real slowing down.
Went back and returned all files to how they were. Had to do that manually as I could not find an auto way (??) but still had no dramas
Not much joy for you having dramas; but I have been where you are now. So why? Why sometime? (for me anyway) There has to be a common denominator.
If we and others (please others) keep posting our dramas the penny might drop at Adobe.