Nice!
One small note: .xls is an older fomat and less in use, but there’s still something odd with them. When you open and close an .xls file in Excel, without doing anything else, it will report a checksum error in DEVONthink. There is no logical reason we can see this should happen. However, if you do make a change, no matter how small, the checksum will be valid.
This does not occur with .xlsx files though.