I have both alloy and steel frame Smiths and like them all. Over the long haul, alloy is going to experience more wear than will steel however proper lubrication can greatly minimize even that level of wear.

The area, other than the external finish, that seems to show wear on an alloy frame is the location where the steel barrel rides in the frame. Running that area dry over a period of time will result in the sharp edges of the bottom side of the barrel under the chamber cutting into the frame.

I've had a couple of used alloy pistols over the years that showed that type of wear. It didn't keep them from functioning though and I have no idea how long it took that wear to occur.