With the Arecont Panoramic cameras, each VMS handles them somewhat differently. Exacq just treats them as four separate cameras and you have to manual place them in order in a layout view to see them in native panoramic view. With our software, we automatically bind all the sensors into a singularly handled stream that gets treated as one camera instead of four. Some VMS even still charge four licenses I'm told but I doubt there are many of those left.
They work great. Customers love the effect, especially with the 180's. 360's are cool but only in certain applicatons. As far as wide area situational awareness, there's no much else to compare with Arecont as you yourself have mentioned about them.
As for Firmware updates, our software allows certain manufacturers cameras to be firmware upgraded directly through our VMS however I don't believe we ever extended that feature to Arecont Vision cameras. I suppose we could if large enough projects requested it of course. Otherwise, the camera firmware updates have to be done using Arecont's method. I don't remember if their panoramic allow you to do it through the cameras web page or not. If not, you'd have to download Arecont's firmware updater application that's part of their internal software. Not an app I would call "user friendly".
The only good news on the firmware side is looking at their firmware release updates, Panoramic cameras seem to have the fewest revisions and new updates pushed out.
For the rest, managing them is no different than managing a large number of any camera make/model Bandwidth is obviously a consideration, mostly since the cameras have a relatively low maximum frame rate, people tend to set them at the highest frame rates they offer. Which of course is like setting a 1080p camera at its maximum 30fps. That and the storage issues associated with that bandwidth are probably the biggest concerns to spec'ing them by the hundreds or thousands.