[Python] What are the pros and cons of importing a class vs. importing the class's module?

I'm authoring a set of python coding guidelines for a team of ~30 developers. As a basis for my document, so far I've studied the Google python style guide and the PEP 8 style guide, and incorporated information from both.

One place where the Google style guide is more restrictive than PEP 8 is with imports. The Google guide requests developers only import packages and modules only, and then refer to items within by a more-qualified name. For example:

from pkg import module
...
my_class = module.MyClass()


The justification is that the "source of each identifier is indicated in a consistent way". For our project, we intend to organize with packages two or three levels deep, so to know the full source of the identifier, the reader will likely need to examine the import statement anyway. I'd like to advocate this style of import as a "preferred style":

from pkg.module import MyClass
...
my_class = MyClass()


IMHO, the readability in python constructs such as list comprehensions is improved when the names are more succinct.

What I'm unclear on is what the python interpreter might do behind the scenes. For example, is MyClass now part of the global namespace for both this module, and all importers of this module? (This would be bad, could lead to some weird bugs; if this were true, I'd advocate the Google style).

My python development experience is limited to about 6 months (and there are not many experts on our project to consult), so I wanted to get more information from the community. Here are some items I've researched already:

effbot - discussion on imports

stack overflow - import vs. from import

python documentation - modules

python documentation - import

Thank you for your responses!

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