I would advise against the strategy of wrapping the Pylons application in a
Pyramid view. I used to do this, but the dependencies in the python
environment are now conflicting between Pylons and Pyramid. There are
packages where the latest version of Pyramid requires a newer version than
Pylons can use. One of the packages was WebOb, but I think there were other
packages as well.
I currently have NginX in front of Pyramid and Pylons applications (running
in Paste) and it decides based on the first path segment whether to go to
the legacy app or the new pyramid application. This seems to be the easiest
method for porting controllers one at a time.