Very intersting article! I was working with both Kafka and ZeroMQ and both of them are really useful, but they are not interchangeable when it comes to designing your solution. You better know which one to pick for the job.

Zookeeper is a troublesome piece of software, especially when running on highly loaded clusters. I had experienced some pretty weird stuff with kafka + zookeeper, where reconnection and rebalancing of topics could break availability quite dramatically.

Another thing, that was not mentioned in the article is that Kafka guarantees the order of the messages, while ZeroMQ doesn't. This is certainly a showstopper for event sourcing applications.

On the other hand, ZeroMQ would be happily dropping messages when the pipeline is not balanced or when there is a spike in the data load. Also better set some sane high water mark, or you will end up consuming all your memory or probably get killed by OOM killer.

Anyway, while both are good solutions be careful not to be mislead by the advertising tone of both projects. Neither of them is a silver bullet...