No idea, I haven't benchmarked a 100% durable redis setup (aof, fsync every query) against FDB but that will definitely have a significant hit to write performa

No idea, I haven't benchmarked a 100% durable redis setup (aof, fsync every query) against FDB but that will definitely have a significant hit to write performance. I generally stick to the model of not using Redis for mission-critical durability use cases. I don't really view them as competing technologies in the first place though.