Kafka has upgraded their producer API in 0.8.1/0.8.2 to have a new Java-based API. It's much improved both in performance, and features. We should upgrade KafkaSystemProducer to use it.
Initially, we should keep the old producer as well, and add a config to switch back and forth. Once we've run it for a while, and things look stable, we can deprecate and delete the old producer.