Derek, I like your idea for a second show dedicated to postwar. However, I would rather see you incorporate "postwar" segments into your existing Notch 6 podcasts for the following reasons:
1. It would give you the opportunity to gauge interest before setting up a second show.
2. Postwar and modern may not need to be separated. After all, large numbers of people are interested in both, collect both and enjoy running trains from a variety of eras.
3. Demographics: Those most likely to embrace technology and tune in to Notch 6 are of the very same age group least likely to have an interest in postwar trains, statistically. The majority postwar enthusiasts I see at our train local train store eschew the Internet, and run Legacy locomotives in conventional only. They are not a tech-savvy group. Certainly, there will be some young people who love postwar, just as there will be older people who love podcasts. In the end however, your demographics are an uphill battle.
4. Including heritage segments in the Notch 6 podcast would diversify your content. Rather than focusing solely on contemporaneous events, or interviews with Lionel or MTH personnel, you could introduce informational and interesting segments from not only the postwar era, but also prewar, MPC or LTI.
Whatever you decide to do, good luck as you move forward!