For me, the big miss with Postgres Aurora RDS was costs. We had some queries that did a fair amount of I/O in a way that would not normally be a problem, but in the Aurora Postgres RDS world that I/O was crazy expensive. A couple of fuzzy queries blew costs up to over $3,000/month for a database that should have cost maybe $50-$100/month. And this was for a dataset of only about 15 million rows without anything crazy in them.