*waits patiently for Carl's end user POC dissertation*
As an integrator we typically have a server or 2 of recent vintage to load demo software, and a plethora of Axis cameras to show all different model types, lens options, feature sets (WDR vs non-WDR). We have similar setups company wide for our wifi systems, phone systems, video teleconferencing systems. As anyone else would, we try to control the amount of outside systems we would be "integrating" with during the POC, unless it was truely integral to winning the POC. We dont run into that on the security side too much, mostly on wireless and voice side of our business (which I dont have a ton of involvement with).
For any new customer we always offer the option to install and get up and running a small pilot system with the full version of the software, and 2-3 cameras. Its really the best way to get the system sold.