When using a low power scope of about 3x or less and using the rifle with both eyes open the field of view is unlimited.
You aren't just looking through the scope as you do with a conventionally mounted optic but you are looking through and around it. You get the whole picture of your target and everything around it. On a moving target you will see trees and openings well before the target gets to them because there is no limit on the field of view you have with this type of setup.
I feel this setup is best used for hunting in the woods, brush gun type of hunting, and I also feel like the straight wall cartridges are the best candidates for this type of system. I certainly wouldn't want to put it on a 26" barreled 25-06.
I know this system isn't for everyone but there must be enough interest to warrant a few scope base manufacturers to make scout bases and Ruger even offered a rifle setup from the factory for the scout concept.
I never really thought much about the scout rifle until I got my 45-70 Handi. I have always liked to mount my scope as close to the barrel as possible, with a Handi you have to go high enough for hammer clearance. I had also installed a peep sight on this gun and hunted with it, I didn't want to mess up the carrying qualities of the Handi rifle. I also wanted to keep the peep sight for a backup sighting system. These three things (low mount, handling and backup peep) lead me to try the scout setup on my rifle and I'm very glad I did because it works great for me.
Another advantage to this system is the non-critical eye relief. I have gotten into situations before while deer hunting when I had to make a shot at an awkward angle and this made it difficult to get a good picture through the scope. I once shot a nice 8 point buck with my scoped muzzle loader, he sneaked in behind me at about 15 yards and I had to twist my body around and rest the butt of the rifle on my bicep to get the scope on him. I knew my eye was to close to the scope but I paid the price anyway to get the buck. This wouldn't happen with a scope mounted out on the barrel.
As you can tell I like the system for a woods type gun. Some like-em some don't, to each his own.
GOOD SHOOTING!
Slufoot