we have look up latency requirements on the elastic side. on pgvector it is currently a staging and aggregation database so lookup latency not so important. Our requirement right now is that we need to be able to embed and ingest ~100M vectors / day. This we can achieve without any problems now.
For future lookup queries on pgvector, we can almost always pre-filter on an index before the vector search.
yes, we use postgres pretty extensively already.