FYI, &display is the replacement of &summarize.
@Ryan: I tried this with the latest Ditto (2.1b3) at Mark’s earlier suggestion -- no joy.
@Mark: &display replaces &summarize -- aha!
@Eol: I tried all the variations of caching and uncaching the call and the page, as well as turning PHx on vs off -- nothing made it work right except turning off friendly URLs.
@All: The production site’s gone live and is working fine. It’s just my local copy of the production site that isn’t working, and I’m having trouble getting FURLs to work properly on the local copy -- so maybe my "Ditto" problem is really a problem in the larger context. I’m going to drop this thread now, and if I ever find and fix the FURL issue then I’ll recheck Ditto behavior and report back if I learn anything new. Thanks everyone (particularly Mark!) for your consideration.