I don't have any experience with the G5 but I do have (2) of the Vipers and they are an excellent sight. The pins are very dim on the G5 sights I have looked at though and even though they bright, I replaced the factory fibers in my Viperwith Fitz fibers.

The pins are easy to change and if someone broke a pin onthe Viperthey were definitely doing something they shouldn't have been doing, they are very beefy stainless pins.