I just put a set on my Kimber Stainless Ultra Carry. I really like the sights, but (after buying them) I have read of a few people who have had problems. These seem to fall into two categories:
--Chemical damage to the fiber optic. Not sure if this is carb cleaner (which is well known to damage plastics) or if damage is being caused by the more common Hoppes/CLP/etc. I would imagine that if I don't blast the sights/slide directly with chemicals, but hit a rag with the chemical and then wipe down the slide, I think I'll be fine.
--Recoil damage. I've read that normal cycling of the slide has worked some of the TFO inserts loose, to the point where they have flown off. Not common, but I won't be happy if it happens to mine.
In the mean time, I will continue to enjoy mine, and I will continue to read up on these as well as other options. As it stands, I am really happy with the choice I made and hope that they hold up. If that happens, I will buy more and install them on my other carry guns.