In addition to the high cost of S3Express, utilizing warpstream to write three replicas to S3Express and later compacting them to S3Standard could result in quadruple network/outbound traffic costs. With two consumer groups involved, this could increase to six times the network/outbound traffic.

Considering a c5.4xlarge instance with 16 cores and 32GB of memory, which offers a baseline bandwidth of only 5Gib, it's limited to a maximum production throughput of 100MiB/s.

Therefore, I have reservations about the cost-effectiveness of your low-latency solution, given these potential expenses.