The BlackHawk USP Serpa has arrived. Reholstering is a bit difficult, but retention and drawing are just fine. I will probably use this holster for open carry from time to time.
For police duty, my Front Line HDL holster has also arrived today. This holster fits the gun perfectly, and its level 2 retention is ensured using a thumbreak/ rotating hood hybrid system, which is less mechanically complex than Safariland's hoods, but requires a different form of thumbwork to get the gun out quickly. I'm not sure what dealerships Front Line has in the USA, but this holster looks perfect to me for duty carry. I have put mine on a police duty belt, with a coil lanyard further augmenting retention.
Anyway, some gun porn: my P07 in its Front Line HDL holster / duty belt: