Obviously I was misreading the eval and never used ppf directly.

Just in principal: If I only need one or a few methods, then I prefer a direct hasattr attribute check or no check at all. And sometimes I run quick examples that uses a quickly created class where I just add the required method.
kstest is another case with many checks or possible kinds of "distributions".

From the discussion and code in https://github.com/statsmodels/statsmodels/pull/412/files it looks like we ended up not checking any method at all. Will raise an exception if required method is not found, when it is used.