Howdy
First off, your question was about Cattleman II durability. The Cattleman II is the new one with the retractable firing pin in the hammer. It has not been on the market long enough t get much of a track record.
Regarding the original Cattleman, which has been on the market for a long time, they have quite a long service history.
I can tell you that the case hardening on the internals of Uberti products is very thin. If one goes at them with a file, one can cut through the case hardening layer very quickly. If one does this the underlying steel is quite soft and will wear fairly quickly. But you have to cut though the case hardening first. The full cock notch on my Uberti 1873 rifle had been subjected to a bad kitchen table action job before I bought it and the hammer soon started following the bolt down, rendering the gun unsafe. I had to replace the hammer and trigger because of this butcher job, after that it was fine.
I have a couple of 1st Gen Colts that are over a hundred years old, and their timing is still fine. Of course, they have probably not been used as much as the Ubertis or Rugers that some guys use in CAS. My 2nd Gen Colts have served me well for about ten years of CAS now, no sign of anything wearing out yet, knock on wood.
I know Ruger heat treats their frames all the way through to make them tough. I do not know if they heat treat the internals the same way, but I can tell you that Ruger internal parts have a larger cross section than the internal parts in a Colt or clone, so they will naturally not tend to wear out as quickly.