Mixpanel will store the data for you and do visualization. Jitsu just help you to get you data to your data warehouse.

Downside: you'll need to build all visualization by yourself. Fortunately that's easy with tools such as Looker, Mode, Metabase etc

Upside: you can do with your data whatever you want - built any reports, join with other datasets etc. You not limited by reports MixPanel team build.

In reality, Jitsu and MixPanel could co-exist. Jitsu support s MixPanel as a destination (e.g. you send data to Jitsu ; Jitsu sends it to MixPanel and data warehouse).