After the Spitzer Oversight Committee meeting came to a close, I got lunch with Heather Knutson (Caltech), during which I picked her brain about things exoplanet. She more-or-less agreed with my position that if any eta-Earth-like calculation is going to be precise, it will have to find new, smaller planets, beyond what was found by Petigura and company (in their pay-walled article, and recent press storm). That said, she was skeptical that CampHogg could detect smaller-sized planets than anyone else has.
Knutson described to me a beautful project in which she is searching the hot jupiters for evidence of more massive, outer planets and she says she does find them. That is, she is building up evidence that migration is caused by interactions with heavier bodies. She even finds that more massive hot Jupiters tend to have even more massive long-period siblings. That's pretty convincing.