Have you benchmarked your load on RDS? [0] says that IOPS on Aurora is vastly different from actual IOPS. We have just one writer instance and mostly write 100's of GB in bulk.
We didn't benchmark--we used APM data in Datadog to compare setups before and after migration
I believe the article is talking about I/O aggregate operations vs I/O average per second. I'm talking strictly about the "average per second" variety. The former is really only relevant for billing in the standard billing mode.
Actually a big motivator for the migration was batch writes (we generate tables in Snowflake, export to S3, then import from S3 using the AWS RDS extension) and Aurora (with ability to handle big spikes) helped us a lot. We'd see application performance (query latency reported by APM) increase a decent amount during these bulk imports and it was much less impactful with Aurora.
iirc it was something like 4-5ms to 10-12ms query latency for some common queries regularly and during import respectively with RDS PG and more like 6-7ms during import on Aurora (mainly because we were exhausting IO during imports before)
[0] https://dev.to/aws-heroes/100k-write-iops-in-aurora-t3medium...