Dave, I read Chuck Yeagers autobiography, and the man had phenomenal vision. Unfortunately, not all of us are equally blessed.... Its the same with sniper selection in any branch of the military and special forces in particular. If you dont have absolutely superb vision, you wont even clear the medical evaluation, let alone any of the training. The physical attributes of members of elite forces vs the general population is just not a valid comparison. Consider also the age of those in the special forces, how many on active duty that are past mid 30's and 40's ? Whats the median age of posters on this forum ?
I definitely love my 3-12x42 scopes and my 4-16x50 Viper FFP scopes even more. I have one 6-24x50 Viper FFP and I would say that the optical quality of that scope does not support more than 20x magnification. More magnification is more demanding of the quality of the optics and it is not a pleasing result when that quality is lacking. I have not yet had the opportunity to shoot much beyond 400 yards yet, I am in Michigan. I'm shooting at coyotes that are remarkably well camouflaged in grass that is often taller than they are. Coyotes are also not the biggest critters you have ever seen, and then the time that one tends to see them is pre-dawn, just as the sky starts lightening. So very low light levels and minimal contrast. We were prohibited from hunting predators at night with centerfire rifles until just a few years ago, so night hunting was with a 22mag and getting close enough for a lethal shot without the dogs hearing or winding you was a major PIA.... Hence sniping them with my 243 at the very start of twilight.
If I could have afforded a larger and higher quality objective for better light gathering, I probably would have, but for the range at which I shoot, 16x is enough magnification. I can see why 5-20 may be a very popular magnification range for people shooting at larger game at longer distances, especially in adverse light.