Well, version 3.0 takes some time to be released, but it is nonetheless very stable. We use it in our production environment, and so far we have encountered a problem (2 years of use). Important issues on 2.0.X fixed by BTW. (it looks like there are currently no major issues on 2.0.X).
BTW. I asked this question on one of the DWR mailing lists and did not receive an answer.
We had problems before (another version), and they were handlers very fast.
December / 2015 update: V3.0.1 released
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