I set up Stitch to connect in to QBO and it's working really well so far. I ended up with the same set of tables. I haven't started moving the PQ queries to point to the new source yet though. Doesn't look like it will be that difficult though.
I set Stitch up to replicate the QBO database every 30 minutes into our Amazon RDS Postgres database. I have no idea what all was involved on the Postgres side - our engineering team handled that. Since we already had an integration with another source set up it only took them a few minutes to get me up and running. Not sure how hard it would have been otherwise. Stitch seems to have things pretty well automated though.