The day has finally come! My decision to keep all objects (Sones, posts, replies, etc.) in memory and never re-create them is finally coming back to bite me in the ass. And even though I knew for a long time that it was coming I was kind of surprised and relieved this morning when I realized why I even did that in the first place: because I thought I had to create Sone (and post and reply) objects before I ever had any real data for them!
Now that I finally rediscovered the reason behind this ancient decision I should be able to rework the parts in question to fit in better with the database changes. Just having discovered this makes me have a much more positive outlook on the whole database topic than I had before. :)