E.g. early versions of ClojureScript had a critical bug on the OpenJDK that gave me the impression that (many of) the core developers are using the Sun package and are optimizing for it. There is also the issue of performance, which is supposedly better with the Sun version, but I should benchmark that for my particular applications before making up my mind. What do you use in production? There is a fine line between an acceptable difference in terms of reliability and speed and being too finicky for production. I'd love to hear more about what you're using.
When you have a proprietary implementation competing with an open, compatible, one, you can have two scenarios:
1- the proprietary implementation is the dominant one and the open implementation must lag behind its roadmap.
2- the open implementation is dominant and the proprietary vendors who want to compete with it have to offer a superset of its functionality in order to compete.
In case 1, you are at the mercy of the proprietary implementor (in this case, Oracle). In case 2, everybody is free to steer the evolution of the standard without fear of getting isolated in an incompatible niche.
And Oracle's #1 priority is Oracle's profit. They'll get it even if it means turning your life into hell.
