I’m one of the devs behind Mixture.
Prepos looks cool and like many of the tools in this area, there are standard features that they all cover.
But Mixture has a lot of features and workflow that are unique.
It really depends on your use case and requirements of the tools, but I would try them both before making your mind up – there is a 14 day trial with Mixture (it was free for almost a year in beta).
I’m not sure why the word “heavy” has been used with Mixture – you can download and start using with zero setup, but it is powerful and feature rich, it also continues to be improved at a rapid pace.
I’ll happily show you around Mixture and it’s features and I think you will be very surprised at how easy it is and how different the workflow and features are from other tools.
If not Mixture, I hope you find a tool / workflow that works for you :)