So how does PostGreSQL compare to MySQL?

the big change in 8.5 is that there will be a synchronous replication via log shipping built into the core. There are already options (pgpool or slony to name a couple) that will do replication and let you read from all boxes at the same time.

I'm not a MySQL expert, but my understanding of the guarantees that it's replication provides make me think that these existing replication tools let you get equivalent safety to what MySQL replication provides.