I wasted Thu and Fri trying mightily to find a magic solution, but I only made things worse. Sat AM, I found a backup in progress and waited (im)patiently. It finally finished in a total time of just under four hours. So, I performed one more SuperDuper backup and ...
With the Time Capsule still wired directly, I booted from the install DVD, erased the internal disk, and began a clean install. I asked it to migrate from a TM backup and it started transferring. After about 90 seconds it said it was finished and presented the login screen with my usual list, but it wouldn't accept my password.
Swearing loudly, I started all over again at 9am. At 10am it started migrating but this time kept going. At 11am it had started transferring with an estimate of 3.5 hours to go. At 4pm (so much for its estimate) it finished, rebooted, and graciously allowed me to log in. Things looked "normal", so I reconfigured TM to use a freshly erased firewire drive, started it up, and called it a day.
Sun AM. The console showed mdworker32 crashing about 20 times per second and the backup taking forever. The crash logs now (perhaps always had) showed which files it was working on. All were font files in a folder that was a copy of the last System 9 disk from just before moving to OSX, most of them dated in 1998! Rather than doing something rational with them, mdworker32 just crumped over and over.
I chucked the folder, rebooted into safe mode, re-erased the TM drive, and started a backup. It finished 162gb in 2.5 hours. But, the console was full of permission errors trying to write to the TM drive. Then I recalled that a TM drive must have UNCHECKED the "ignore ownership" option. However, Get Info doesn't present that option at all for my (any?) firewire drive. So ...
I rebooted to safe again, switched TM to a USB drive, with that option unchecked, and started a backup. Done in two hours and ... NO CONSOLE PROBLEMS!
I rebooted normally and started a backup. Done in 3 minutes!
I performed another SuperDuper backup, for the sake of sanity, and declared victory.
Mon AM. Backups are now taking about 10 minutes, still no problems.