I've made good experiences with that combination as well, and it is very noticeable that Pyramid was truly designed with extensibility in mind (just look at e.g

I've made good experiences with that combination as well, and it is very noticeable that Pyramid was truly designed with extensibility in mind (just look at e.g. using different or multiple template engines or using a different ORM). Pyramid also largely avoids magic (unlike Django and Flask, though Django likes magic a lot more) and global state (in a clean way, not Flask's put-everything-in-a-function way).