Hello Benjamin,
having followed what direction OpenACS is going, I can tell you that very little changes will be made to the db_* API: all new development takes place in XoTcl + Nsf now, at least in the core team.
You're right about the big deal of replication one can incur when forcing a logically OO model onto a procedural language: you always end up writing the same procs (create, update, delete, read... boring) on tables that can be very similar.
Fortunately, the new OO API addresses a lot of this: one can define an object in a very declarative way and this will bring to you table creation, acs_object inherithance and all the CRUD methods for free. It is a big leap forward compared with how I am still used to develop (our codebase is currently all-procedural).
If you want to start digging as I did, you could consider this tutorial http://alice.wu-wien.ac.at:8000/s5-xotcl-core-tutorial/slides. Sooner or later I was thinking about writing a little demo package showing some of the OO potential of OpenACS and letting you fiddle with it. In the meantime, you could have a look at the code in xotcl-core package
All the best
Antonio
