Hi Rob;
The primary reason I thought I'd try the auto write to xmp is because, when I do a large batch of writing metadata to file after a week or two or editing, many of them will still come up as not up to date the next time I look & I must go to the additional step of writing from file back to the catalog. It doesn't seem that Adobe is ever going to fix this bug & I thought I could avoid it by automatically writing to xmp.