Michael,
I did a bunch yesterday and no problems, 40-50!
JC,
I'll disagree with your "adding new keywords will not help the image move up on the search", because it does and did on ALL the new edits! From being about 20 pages back to the pages, 3,4,5 area. Some even better!
I think that this would also be a good tool, to verify certain keywords are in old uploads,without going and looking at every image and keyword group.
I found, my best sale from Glacier back in April,2012, a giant 4'x6' print. I got the dreaded email on a Friday, that the image wasn't good enough to go that big and worked all weekend, deleted the old image and the old keywords(this was before I found out that you could just delete the image itself and keep the keywords,description) and uploaded a better image and was sold. Unfortunately, I fogot to re-upload ANY keywords!!! So until I found this out yesterday, manually going through each image, it was there, but had no keywords and may as well been blank! See above for the image.
Rich