There are some great commercial options in this space like SignalFX and Sumo Logic. The cost of Riemann's learning and implementation challenges would have to be made significantly less for entire teams to make it a viable alternative to those, in my experience.

If anyone runs a team of 25 or more SREs and effectively uses Riemann (and there's more than 3 domain experts), and is not otherwise a Clojure shop, I'd love to hear from you.