I understand now, and that is very complicated. Basically you want a normal podcast channel and a premium channel, and you want the premium channel to also include the normal channel content.
I think in this case, category based podcasting rather than channel based podcasting would work better. Unfortunately, we did not develop the custom podcast channels to work with categories because of the complexity of mapping podcast channels to categories (it would get complicated very quickly).
The only problem with category podcasting is that all your episodes would appear in your main feed. This is done on purpose, in case PowerPress fails for what ever reason, your podcast episodes still get picked up by WordPress.
My only other thought is you may be better serviced making a copy of your post with separate dates since you want premium users to get the content a week before regular users. There's a plugin called Duplicate Post (
http://wordpress.org/extend/plugins/duplicate-post/) that I use to copy posts, it may be useful for your situation.
I'm going to think about this over the next few days, there may be something we can do to simplify what you want to do but I'm not sure how easy/uncomplicated it would be.