Based on the discussion about optimum pinhole size I decided to try one in my 38mm camera that was closer to the 0.25mm size. One nice feature of my home-made camera is that the pinhole disk is held in place over the shutter by a little donut of foam, so switching it out is just a few minutes work.

I couldn't really see any real difference in sharpness or other characteristics of the image produced by the new pinhole over the old one. That's fine with me as it seems to show that optimum has some room for negotiation. The currently installed pinhole is from the set of a dozen I bought from the fellow on ebay. This one seemed a bit rounder and smoother than the first, so I didn't do anything to it except to trim the disk to size.
This image was the last of my Delta 400. On this occasion I rated it at 200 and developed in Rodinal at 1:25. I like the results better than what I was getting from the HC-110. Now, I have to order some new film. I think I'll probably go back to APX for another round. I may also look for some very slow stuff to get a little more control in bright light.
I've got a laser-drilled pinhole coming in the mail. I'll be interested in seeing how it performs in my camera, and am also thinking it will be helpful as a kind of baseline for other efforts.