The problem with the "snap roll" failsafe settings is that you could well end up with a brief lockout that causes the plane to veer violently, perhaps towards bystanders (due tot he elevator/aileron settings) before control is restored -- which means the controls will now be at neutral and the plane will stop snapping and start travelling in a straight line again..

How many of us have the reflexes to then regain control and steer away before encountering the ground or an object on it?

Remember -- one second the model will be flying normally, the next it will have snapped to some wild angle/orentation. Your brain will have to determine the heading and apply the necessary inputs to correct it. I believe the average reaction time of even a good pilot will be significant fraction of a second under ideal conditions -- how far can a jet (even after some fraction of a snap roll) travel in that time?

There's no "best" setting for failsafe that will cope ideally with all possible scenarios and it's been my experience that momentary lockouts are a lot more common than total, long-lasting ones. If that's true elsewhere then the snap-roll failsafe setting could me even more dangerous than "last position hold".