Hi Gary, glad you found it useful.
I wouldn't class it as "perfect" myself, all the metadata source plugins I have written each have their own strengths. For instance FantasticFiction has lots of covers and good series information, but no ratings. Goodreads is my favourite "all rounder". B&N usually has the best covers. I tend to have (only) those three sources enabled. I would use Webscription too for the small subset of books Baen have, but disabled the rest of the time.