From the current version (0.98) of the Moose::Manual::MooseX are the lines:
We have high hopes for the future of MooseX::Method::Signatures and MooseX
It depends on what you mean by "production ready". I wouldn't depend on them until their velocity slows down quite a bit. I like my production stuff to not need frequent care from external code changes, API adjustments, and so on. That's not something particular to Moose, but any young project.
You have to judge how much that matters to you. In some situations, pushing stuff into production is a lengthy process, so you must be circumspect with such things. At the other extreme, some places let you edit files directly on the production server. That is, you have to define your tolerance before anyone can tell you which side a given MooseX module is on.