We also do have some benchmarks comparing real-time performance, which are under submission at a scientific conference, so we cannot share them yet.
Unfortunately, testing against Firebase using established benchmarks such as YCSB is not very useful, as it's unclear which limits are enforced on purpose and which limits are inherent to the database design. Would you be open to providing a Firebase setup for heavy load testing w.r.t. to throughput, latency and consistency?