Hiera and r10k, roles and responsibilities

[Antony Gelberg]

I'm looking to set up a new Puppet infrastructure, which will manage several environments (nothing fancy, let's call them sandbox, staging, production). Given that I can use hiera to differentiate data by environment, is there still a use case for r10k? If so, can somebody give some examples of what that use case is? In short, one "master" branch and hiera seems a lot simpler to maintain, but I'm concerned that I'd be missing out on something useful.

I know that r10k is also used for deploying modules, but librarian-puppet can do that anyway, so I also. Is librarian-puppet still in use? Most of what I read about it is a few years old.