Thanks for the responses, everyone. I understand the part where winning a reader with a free ebook might win you readers for your other, not free, ebooks. And indeed, I've seen that occur with my
other ebooks, available at your favorite ebook emporium. And, to be clear, quite a few readers have responded generously with donations for the free ebooks.
But from the point of view of the economics of writing, paper books are still where most of the money comes from. And one's standing with one's publisher, and with all the wholesalers and bookstore chains, depends far more on the sales of one's current p-book than anything else. So, it's possible to make encouraging inroads into the ebook market, but get killed in the paper market. (And many authors, not just me, are getting killed in the paper market, especially mass market paperbacks.)
I don't really think that offering free ebook downloads
hurt my p-book sales, nor does my editor, but I am wondering if, or how much, they helped. (Dang, what I need is a parallel universe where I did things differently, and then I could really tell.)