I have had no issues with installing and the maintenance on POE solutions. Most of the time if I am doing a camera replacement I will swap like for like unless there is a good reason (eg the customer has recently moved to an IP VMS).
The only point I would like to point out is it makes troubleshooting a little more complex especially if its a shared site and someone else will be performing the maintenance that is more familiar with legacy solutions.
The main issue we have run into when trying to put IP cameras into elevators (retrofit) is that there might be twisted pair travel cable, or coax, already existing; but no Category-type cabling.
You then have to put in Veracity or Comnet PoE over twisted pair adapters on each side, or the same adapter in a coax flavor. We have found that the elevator support contractors will gouge us to add a Category travel cable. The last quote we received was for $8000 to add one cable to a 2 Floor travel elevator...
Also you want to look at the M31-R model cameras; Axis might not honor the warranty or give full support to a non -R type camera installed in an elevator (or vehicle).
Category cable is not rated to be attached to a travelling cable and Cat cable is not one of the cable types in standard travelling cables from the major manufacturers.
I’ve seen a fluid mesh link installed in the shaft work very well. One radio on top of the cab and the other on the ceiling of the shaft. Done.
We are using Axis M3006 IP cameras in our elevators.