The e4s_product.yaml file presently lists which files are present in each product repo. I think it would be better to discover which files were present by looking for them as part of the raking process. This way, product teams could add a new file and it would be discovered automatically.
In general, I think it would be better to have no information other than the base URL in the e4s_product.yaml file.
Perhaps you are already moving in this direction, but want to make sure.