I guess I'm just blessed.
I've backstabbed everything I can for 30+ years, used wago's for at least 10 years, and haven't had a failure that I'm aware of yet (when the wago or backstab device was properly installed)
I've had a few wirenuts fail (probably not installed properly), seen backstabs by others fail, seen purple nurples catch fire, seen tons of crimp connections fail, but never a problem with properly installed wagos or back stabs.
I have seen many backstabbed receptacles fail. How do I know if they were installed correctly or not?
I have also seen screw terminals fail, just not as many.
I have never seen a failed wago type connector. I keep a few of the Ideal brand handy. They are great for dealing with short wires in small boxes. So far, not a single problem, but they can be a bugger to install correctly. It's a good thing you can see through the ends as sometimes it's nearly impossible to get a wire in there. Old 12 AWG NMS has fat insulation and really has to be pushed in hard to seat.
For connecting just two regular solid wires, I think I can actually put a wire nut on faster, as the wago types can fight you. But, I guess, if they just slid in with no friction, they probably wouldn't work very well for very long.
Another downside of wago types is the impossibility or extreme difficulty in removing the conductors without having to cut the connector off. Sometimes it's nice to be able to separate conductors for test reasons. It would be nice if they came up with some sort of removal tool or procedure that would not damage the conductor and would be fairly easy to do.