> Should such custom collection classes be defined in the schema and therefore been generated at generation time?
Also it would be cool if typehints/docs would be adjusted by the generator to bring in type safety and make IDEs aware of the collection types...

I would love this to happen, but I'm missing the insight for now, and would probably miss a lot of things at the end. Just started using Propel2 in a new project and diving into it. However this idea is very old, see #266 :)