> I can't implement PITR right now on our live systems, for > commercial reasons.
What do you mean? Most of your email seems to describe techniques very much like PITR; why would that be OK but the existing, tested PITR not be OK? It's hard to know what to suggest without understanding the answers to those questions.
PITR is a one or two line update to the postgresql.conf + a base backup. What you're talking about is trying to build your own version of this (significantly more complex). What are the 'commercial' reasons that you have for not using PITR, ISTM that you'd really be wasting time not using it.
