> ELK can't, for instance, store 20G of logs today with no parsing applied, and let you parse out key-value pairs and graph all the latency numbers next week.

> ELK can't, for instance, store 20G of logs today with no parsing applied, and let you parse out key-value pairs and graph all the latency numbers next week. This isn't entirely true, you can have a generic logstash-* index and dump log lines into it (say sending from syslog). All you need is a timestamp and a string. Later on you can reindex that data at anytime, using logstash (and/or elastic curator) and then reinterpret that data into a different index in which you will be able to graph on Kibana.