So, to sum up:
Also, Atomz will index long texts, like the novels at the Wharton Society site.
Picosearch also puts a more or less random date on the pages; for example, several pages have been updated since June 2005, and the site has been reindexed since then, but Picosearch still shows June 2005 as the page date.
Since the point of a search is to give complete results, it looks as though Picosearch wins this round. I've put Picosearch boxes on the Timeline pages but am sticking with Atomz for the places where long texts need to be searched: http://www.edithwhartonsociety.org/books/index.html
UPDATE (for those who care): The problem seems to be that Atomz has a hard time figuring out text that's in tables, and there doesn't seem to be a solution for that.