It takes less than a second to determine the correct range and have your target in the cross-hairs. You don't have to turn any knobs either.
That said, I still love my 30.06/Model 70 Standard weight with the Burris 4-16. I zero at 200yds, never shoot over 300yds with it........
The 400yd shot was an anomoly for me, I knew I could do and successfully took the shot with that Browning .308.
I helped set up my friend's Shepherd scope and I did use it at the time so I know about them. If I had to confront same size targets at various ranges quickly with the clock running, I can't think of another scope that I would use. I like the Leopold's for known distances like Silhouette Shooting. What exactly is sub-second?