Maya,
As I note in previous response, I just learned about category URL, but cannot test it because relative URLs are not accepted and I'm in pre-published mode. Does the category page also have pagination so there is not the endless page scroll? After reading a post from the category page and closing it, where is the visitor left--still at the category page? Unable to test the category page, I still have questions like these.
The problem with jumping from the Custom Feed when reading a specific post is that the visitor is taken away from the page. It's confusing and a navigation problem. They can't easily read numerous posts that way. And of course the custom feeds can combine categories for special purposes, which is not the case with category URL.
I still recommend having the option to have posts display in a popup window when reading posts from a custom feed or recent posts feed. Alternatively, the system should keep track of which page and where the visitor accessed the post (in the main blog, category URL page, recent posts feed on page, custom feed on page) and return them to thet point when the post display they are reading is closed.
Thanks!