@Inline6, I completely agree with you. They have certainly extended my range from a standing position compared to the older bipod or tripod sticks. I have yet to shoot anything over 200 yards in the field with them but on that 200 yard shot I was very steady. And if I get support for my right elbow from a tree or PH etc. I feel nearly as steady with these sticks as on the bench. My son has taken game in Africa using the Viper Flex (my PH had a pair and that's what made me get them) at around 400 yards (I know this is an unusually long shot for Africa but it was a big Nyala at near last light and we did not think we could get closer without spooking him)
Took my zebra just inside of 300 yards going up a hill on the move with them. That was the first time I was introduced to them, like @Tucketed my introduction was with @JKO HUNTING SAFARIS I carried my competition tripod setup. That is what I was going to use. It is more precise at the expense of speed. The Viper Flex give a good balance for hunting.
That's good shooting on your son's part, 400 yards it a good shot.