The most compelling use case I've seen where Passenger loses to Unicorn is rolling restarts. The biggest trust issue that I've seen is that of source editabili

The most compelling use case I've seen where Passenger loses to Unicorn is rolling restarts. The biggest trust issue that I've seen is that of source editability - Unicorn and Mongrel are easier to debug and patch, while Passenger requires a commanding knowledge of Apache to fix.