I'm currently going through the 3DBuzz Developing modular rigging systems with Python, and Containers are a huge part of their process. I plan to finish this tutorial series, and write my own auto-rigging toolset. I have other ideas in mind, and another approach, but I just want to finish this tutorial first, not sure why Anyway...
Personally I never really used Containers in production. I've googled a bit more about what people think about Containers in Maya, and I found mostly positive feedback.
However I don't see any auto-rigging scripts that use Containers, including big ones like Advanced Skeleton and I think A.R.T too (actually not sure now about this one) for example. I think I only found one Modular auto rig, that was using containers as part of it's workflow.
I see the appeal of Containers as a way to Lock the rig as much as possible for animators (probably useful on big projects, but in most cases in my experience I did not have the need to protect the rig THAT much). But I also see some downsides. For example it makes maintaining this rig harder, it makes it harder to work with it for other riggers. And in auto-rig scripts it adds a lot more steps to include containers as well.
So, what do you think about Containers? Are they really useful? Are they worth the time spent on setting them up and learning all ins and outs?