Our 1995 Scamp
came with its 110 outlets wired up using the push-connectors instead of the screw terminals; elsewhere there are nutted connections as well as screw-clamp connections at the breaker box. So far, all of them have held up.
I think the main thing with wiring isn't what kind of connector you use, its making sure the connections are done right and setting things up so the wire doesn't move around as your trailer bumps down the road. Excessive movement will cause metal fatigue in any connection.
Thinking of which, I do have one electrical
connection in my trailer that does give me trouble. The clamp connectors that hold the wires to and from my solar
charge controller in-place. They're cheap connectors and the wires keep wriggling loose. When I have some free time (In January? I hope?) I plan to "upgrade" the setup by adding a screw-down terminal strip to my setup and soldering the existing terminals to it with some 12g solid wiring.