Here’s my progress, so far.
I spent several hours re-entering all my data by hand on a freshly generated profile, native to 1.0b16. So far, it appears to be working as expected.
One difference I noticed is the existence of DNS entries for kerberos, specifically an A record pointing to myself, a TXT record with the kerberos domain, and several SRV records for kerberos-adm, kerberos, and kpasswd. These were NOT present in my older DNS data, and were not added by the upgrade process from 1.0b12->14, or 14->16.
IF something relies on those entries being present, that might well be the cause of the hang… however it’s only a guess.