One thing to remember is that there has been a lot of work done on the test suites (thanks to Schwern, Chromatic and other unsung heroes). So even though the language gets more complex with each release (with Unicode support for example) you can also be a lot more confident that glaring bugs will have been caught.

So in short my bet is that 5.8.0 is a lot more stable than 5.6.0 was.

5.9.n OTOH will be a development track, so it might not be such a good idea to install it on a production system.

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The Error Message is GOD - MJD