I run two self hosted instances, but I’m also biased as one of the founders 
The risk level on update, as long as you are only using official plugins from Discourse, is fairly low. If you are using third party plugins, the risk is considerably higher.
Our release schedule is roughly
- beta every few weeks
- release every 6-8 months
Meta, this site, runs off the latest checkins. We have an extensive test suite, smoke tests, and we tend to respond rapidly when something is broken, because it affects us here on our own support site.
Hope that helps, enjoy Discourse 