[AJY]

That picture you have is of the Ranch Products mount. I have one that was mounted on a GB. Best mount out there for a scout type set up. Only problem is if you want to mount a Holsight or similar type sight that needs a MILSPEC rail, as the rail is slightly wider and a different shape ( I had to modify mine with a dremel). It's great for rings and a scope though straight out of the box.

 

[AJY]

You can still see the front sight (most of it anyway), but it takes a little longer to pick it up. Also if you have a GB with the winged front sight you have to make sure you're looking at the front blade and not one of the side wings. I currently have an Aimtech Scout Rail on mine, and its the same deal, you're looking at the front sight through a tunnel. I painted my front sight blade with flourescent red paint to make it easier to pick up-it helps alot.