For the record: I got the call-back, took the 2nd interview, and was offered the job. I took a day to mull it over; asked around town, talked to a few people, and politely turned it down.
As far as “real jobs” go, it would have been the 2nd-best-paying job I’d ever had, and almost certainly the most secure. The employment conditions didn’t look as bad as I’ve had to deal with in the past, but neither did they seem all that outstanding; why go backwards or stay the same when there’s an immense future before you?
In other news, the first cheque from my new business venture arrived, along with a letter expressing interest in further future consultation. That, and another appointment coming up this week, have buoyed my mood considerably.