I did the same kind of competition, and the double-aperture sights were, indeed very effective and effortless to use. There's a catch though: they're only good for shooting circular targets of the correct apparent size.

I actually did once use a rifle with such sights to take some small game. It was not easy to aim outside of the conditions for which it was designed.

I think it depends in large on the type of shooting. I didn't have a problem with double peeps for man-shaped targets, but acquisition is harder due to the limited field of view.

The military style peep + blade is a good compromise I think, especially when have to worry about ranging.