The FOs have no tritium insert riding in front of it like the TFOs or TFXs.
I am willing to bet the TFO and TFX sights have the same durability. I think the two big differences between the two sights are:
Rear sight picture. The TFO has rounded corners on it's rear sight picture. The TFX rear sight picture is has 45 degree cutoffs, like the Novak tactical wedge.
The front sight has a colored outline. You can get an orange outline, which is something I really like.
I think the TFX sights are worth paying extra.
I am willing to bet the TFO and TFX sights have the same durability. I think the two big differences between the two sights are:
Rear sight picture. The TFO has rounded corners on it's rear sight picture. The TFX rear sight picture is has 45 degree cutoffs, like the Novak tactical wedge.
The front sight has a colored outline. You can get an orange outline, which is something I really like.
I think the TFX sights are worth paying extra.