I had the chance to attend a Scriptrunner session as part of the Atlassian User Group meetings, and I learned quite a lot; I got a sens of what Scriptrunner can add to Jira, and how it can add complexity that affects maintenance and upgrades. From what I gathered, depending on how far your scripts go, you can be digging deep into the undocumented guts of Jira, and Jira upgrades can render your scripts inoperable when those guts evolve.
So my question is this - it's clear that there is a level of complexity and risk that Scriptrunner adds, but how much so?
Bonus question: for admins who are not 100% dedicated to administration as part of their daily duties, does this level of complexity/risk increase exponentially?