The major value added is better error messages and documentation. Marpa::R2 is stable, and I'd held off on making an indexed release of these improvements. But I've been "eating my own cooking" a lot recently -- using Marpa::R2 for large parsers. And this has convinced me that the small improvements in some of the error messages can have big effects on the user experience, enough to justify a new release of even a stable module.
Thanks, jeffrey