I GM and have occasionally played in two games that use a hero/fate/whatever option. That is Amazing Adventures and BASH. AA uses fate points that can keep you from getting hit, effect the plot in a minor way as well as other stuff. BASH uses hero points and hero dice. Hero points let you spend dice to help with a success. Let's say you need just 2 more points to keep that atom bomb from going off, you can do that. Hero allows you do things like appear somewhere that would not normally appear at, add to a die roll by rolling an extra die, and my favorite, the power stunt that allows to do something unique with your one time in a creative way. The key to these mechanics contrivances is that they are finite. You don't have an unlimited number of these so they need to be used judiciously. You basically save that mechanic for the time you need it.
So far it has worked out fine.