Thank you, Thomas and Alan, for these helpful replies, and thanks, Alan, for the link to the pictures. I'd post a picture of my own except my scanner is packed up in its box in the closet. The density build-up along the border between shadows and mid-tones/highlights is very striking with the dilution and agitation rhythm mentioned above. It's nice for some subjects, but too artificial for others.
Apart from the bright fringes everything else is fine - tonality, contrast, shadow detail. The negatives are very easy to print.
Since I'm starting from a 10-minute agitation cycle, I think I'll come down to 5 minutes first, reduce the time from 45 to 30 minutes, and see what happens.
Thanks again,
Brady