I've talked to a number of people who have had the FO rods fall out. Had it happen myself with some mounted on a shotgun.
Personally, the FO type sights still seem to big and fragile to me. I still prefer the three dot night sights. I do like the idea of the TFO's, but I'm waiting for a better set up, if one eventually comes.
As far as level of light and night sight usefulness, it doesnt have to be dark or even night time to benefit from them. The tubes glow all the time, and will give you a sight picture against a dark background where you would not get one with traditional sights. They are also much easier to pick up quickly when you move from bright into shadows or darker rooms, etc.
Regardless what you use, a good light in your pocket (as well as on your gun, depending on your use) is also a desirable accessory. Like a map, compass and GPS, somethings that do work well alone, work better together as a package.