Mine is wet UFH. The system consists of manifold, pump, thermostats, actuators and Tubing full of water under the floor.
The system was about 10 years old and effectively the whole system bar the pipes in the floor was all replaced with new for about 800.
In one of the bathrooms floor was lifted and replaced to overhaul the bathroom UFH in the screed was left untouched.
So if the plastic pipes buried in the floor leaked that would be a problem but really everything that might need work is above ground and maintainable at prices probably comparable to overhauling a radiator system of the same size.