Worked at a company that suffered from this too. Compounded by the feature that let customers share data with other customers, so single DB was a decent archite

Worked at a company that suffered from this too. Compounded by the feature that let customers share data with other customers, so single DB was a decent architecture to begin with. And we were on postgis v1, which had no straightforward upgrade path to 2.0, nor was it supported by later versions of Postgres. Restoring a backup became a multi-day affair.