Allen Pike, on why such an app doesn’t exist yet, and is not likely to exist anytime soon:

The next step, the final step before going all in on building this, was for me to figure out how to make it sustainable in such a niche market. I just had to do the “napkin math” to show that if we built the app, we could maintain it at a level we could be proud of. This step has proved problematic.

Unfortunately, it looks like the potential audience for an advanced, high-quality podcast recording app is not large enough to make it sustainable to develop — and more importantly, to maintain.