Thanks Mike.
Yup here my analog Optex cameras are using a CCTV PDU. I originally ran catXX (X2), coaxial and power cables.
Over time went to using catXX baluns for just video then later for video and power.
Today all of the new IP cameras are POE connected. This too changed a bit as earlier IP cams were not POE.
Then too Ubiquiti went with a different voltage for their POE cameras.
I am guessing if you still need a heater for a camera you would have use something other than POE.
Early days of POE when there wasn't any was done by Cisco. It did change.
In a commercial environment initially utilized propietary Cisco AP's (and VOIP) with POE to Cisco POE switches way long time ago.
The standard did change and it was different than originally done up by Cisco.
Personally it does work fine for residential use CCTV.
I am noticing is propietary combo POE switches / VDR stuff and wondering if this has to do with the power draw on the IP cameras. I mean most of them are rated at 1 AMP and come with a 1 AMP power supply. Many of the little POE switches are made for VOIP telephones and typically have draw amperage limits total and per port. I am currently using POE for my tablet top touchscreens and cams and it works for me.
Later came the Axis IP cameras initially done up with a local power supply then POE. The issues that I dealt was was mixing of the security transport (CCTV) with the rest of the enterprise network and the volumes of traffic generated by the cameras. Networking, network security and CCTV stuff all had their own money buckets (well play money) such that there were charge backs relating to upgrading the infrastructure and that caused some issues. Today I do not know if it does cause issues in commercial money bucket environments.
That and every little piece or mechanisms or topology of transport you put between a light (or whatever) you do decrease the resilence a bit. A light is a light is a light.
If the use of POE continues with different stuff not typically utilized (well like LEDs) then the POE standard might change again. Thinking though we will hit those limits of what you can pass on a CatXX cable really soon.