Also, the principle of "if it ain't broke don't fix it", has several asterisks and caveats in practice-
There is the set of broken things you haven't yet felt the pain of, which are being fixed.
There are things like feature additions that don't really fix something broken but are desirable.
In general, I would say, be confident that you can get back to where you are if newer versions present problems - but, still, upgrade somewhat regularly, at least to released versions. The most conservative approach is to upgrade to released versions after some stabilization time period. Since 3.13 was back in March, there has been ample time to see if major bugs had surfaced... I can understand not wanting to run the daily build, but, 3.10 is ridiculous. Go for it.