For video surveillance, the 'benefits of IP' have generally trickled down, even to an end-user level. When it comes to networked cameras, attributes like HD resolution, centralized storage, and common ethernet networks are all given as advantages (among others) for choosing IP.
However, for those selling physical access control, what justification do you give for recommending an IP based system over a 'traditional' hardwired or serial connected system? What attribute of IP Access systems carries the biggest weight with your customers?