For most practical purposes, no matter how you set it, the only thing Fail Safe does for you is change the place where you crash.
And, while that is true, you have to look at the other side of the coin:
A plane without an active fail safe is going to continue on at the last control setting until something stops it, being something, someone or the ground.
A plane with an active fail safe, unless you lose the batteries, is going to respond in a planned, predictable manner and will probably come to a stop in a location that is much easier to find and get to if you don't regain control of it first