I have one running with a ~5TB big unpartitioned table.
Adding ~9M rows per day, with significant read load via 2 replicas. Works just fine on a 32 GB memory RDS instance.
There is another table half the amount of rows and I join the two 1000s of times a day.
Took a bit of fiddling around to have things run stable. Currently migrating to Redshift, which has stellar performance but comes with its own problems.