Nice! Great point about the round trip - we do something similar for formulas and auto-generated fields like `Id`. That's awesome you built this in-house.

> Syncing data from Salesforce (to seed a database for example) is done via REST too. It works OK.

Have you thought about using the Bulk API for seeding? We started relying on that instead of REST, which helped us seed massive DBs much faster / more efficiently.