I've considered buying each one in turn, and decided, for now, not to. They arguably would be an asset for someone who looks to sell usage of their images.
For me, I don't want to wade through long lists that have only passing relevance to the way I think of my catalog. I have taken a hint and structured (loosely) my keywording in the hierarchical way those lists are organized. But I have locations only for the photos I have. And I'm not keywording for others to find my images, but for me. And that, I think, would be the main deciding point.