Tritium vials fall out occasionally. They all have failure their own failure modes. I have heard the argument that fiber optic sights are fragile and break, but I have never had one break because they are ruined by oil (coating dissolves and no longer traps light) and need to be replaced before that point. Even if the fiber does break you still have a black front sight with a hole in it. There is one company that makes a combination Tritium and fiber optic front sight, but I have heard complaints that the expensive rods can be ruined by solvents.
CT batteries do die, and it is definitely a consideration, but that could be considered a maintenance or carry rig issue. If the laser is being activated as you carry then something needs to change. Hopefully you find out there is a problem when the batteries die sooner rather then later when you need it. Regular replacement of the batteries on a schedule is a must.