Carefree mode requires at a minimum a 100% reliable and accurate compass, preferrably a full GPS/compass. Even in the best of systems it may not be 100% reliable and becoming dependent on having such a feature is IMO not a good thing to do. It may be a better option to become fully proficient in flying all orientations and rack up as much stick time as possible to make it reflex and not something you have to think about while flying then make sure to either stay within a line of sight where you can determine the orientation of the aircraft or have a means to see where it is and where it's going if beyond line of sight. If that means adding bright LEDs in some manner then by all means do it. If there is a need to fly far enough that visual orientation will be an issue then either a good FPV system to be able to see where the aircraft is and the direction its facing or a waypoint flight system that doesn't require the pilot to maintain visual orientation would be more useful.
Bottom line, carefree mode is not a substitute for being a proficient pilot comfortable with flying in any and all orientations, you need to be able to fly your way out of trouble and not rely on hardware or software to do it for you IMO.
I have several multis with a carefree function and its turned off on all of them.
Just my $.02...
Ken