Note that I replied to a different version of the parent comment. Thanks for updating.

Personally I started using zeromq, but was a bit disturbed by the experience of the saltstack guys with timeout problems and memory leaks. Probably fixed now, I should think. But more than that, the LGPL and MPL 2.0 licences aren't great for a commercial project that might in future need to be distributed to a different entity. So the license alone is a reason one might welcome greater diversity in available choices.