"FO pros:
1) great for quick acquisition, so very popular for competition.
2) Very bright in daylight.
FO cons:
1) Not visible at all at night, even with a flashlight or other light (at least not to me).
2) They can, and do, break and fall out.
3) Very tall front sight post typically."
I was in an indoor steel plate match last week and I noticed # 1 this as well. I had just replaced the FO sight on my Shadow 2 with a green Fiber (the red one fell out as it also did on my buddies ) and it was nice and bright.
Inside the range under much lower lightI felt like I almost had to point shoot. the thing disappeared.