The plugin package (zip) files were upgraded last time on 1st of April and I have tried to keep myself away from all maths or plugins during the summer (holidays) so using them on a production site may be risky since there are no help files / good documentation for students etc and even the moodle docs may have "old information"... For example the text that Colin has written to moodle 2.0 docs contains newer text than moodle 2.1, 2.2 or 2.3 docs because moodle docs has some automatic way of cloning some old docs with old content and changes should be made to each moodle docs page version /20/ - /21/ - /22/ - /23/ ... separately.
Check for example http://docs.moodle.org/20/en/Advanced_Maths_Tools#Additional_HTML (2.0 docs) and compare it to http://docs.moodle.org/22/en/Advanced_Maths_Tools#Additional_HTML (2.2 docs have old MathJax 1.0 code)
There are also some browser specific issues, mobile issues and other such things that single testers (administrators or teachers) can easily handle by changing browser (to Firefox) or device but students may find it very strange if Safari suddenly freezes in editor when they try to add some content with java tools or IE8/9 can't handle google chart wizard or geonext applet output in jsxgraph plugin...
It is of course possible to disable unnecessary plugins/filters or use course/user themes to allow only certain courses/users to use the plugins but you can as well add only the necessary script tags to additional html (or even single course page) for rendering mathjax, jsxgraphs etc and copy/paste or import maths from a test site to a production site. Personally I have still used the plugins only on my test sites - not on our production sites.