@GilesR: My $0.02
Serial control is ancient. makes for cheaper cameras, but presuming wanting to buy something that will last for years, buying a serial controlled PTZ camera now doesn't make sense, to me.
But... Depends on your Sanctuary layout, lighting, priorities, target resolution and frame rates, and budget .. feel free to DM me, or start a thread on its own this for more on this discussion (as its off-topic)
High-level feedback - The price premiums on NDI PTZ cameras from a couple of years ago have diminished, and breadth of offerings has increased on NDI PoE PTZ cameras, with a range of optics/sensor options. Smoother Pan/Tilt/Zoom motors (ex handling moving cleanly in the diagonal) and low-light capability with low image noise costs money. The trade-off for those NDI capable camera costs is the convenience of MUCH longer capable runs (vs HDMI, USB, etc ... SDI can be longer but has its own legacy issues), and a single cable for Power, Video feed, and PTZ control. For a single camera setup, near the OBS PC, NDI could be overkill. But as soon as you start talking multiple cameras, presumably dispersed, ease of single cable wiring, etc... NDI for the win ;^) The only counter-point that comes to mind is certain worship styles that place cameras mid-crowd and pay crazy amounts for highly-reliable dedicated wireless connections (NOT consumer WiFi. I avoid wireless whenever possible for reliability and consistency)... oh and maybe historical buildings where even cable runs are a big problem ... but I've been in old stone mason cathedrals and the wiring for the PTZ cameras (and speakers) isn't obtrusive... so yea, I'll still default to a wired connection
Am I rationalizing my own NDI PTZ camera choice from 3+ years ago? maybe... but I haven't seen a good alternative (and IT Infrastructure is my area of expertise). Really it comes down to budget. My choice then, and still would be, a single NDI PoE PTZ camera vs 2 cheaper non-NDI PTZ cameras (for approx same price). With a good quality PTZ camera, at least for us, live camera Pans look professional and smooth, and we have no complaints. The alternative is cutting between 2 cameras. With a higher-end camera, we also get excellent low-light capability.