The bigger your peep sight hole, the better chance you will have of bein able to see your pins.

I use the impact cosmic along with an open peep(looks like a " C" ) not sure of the formal name for it. Lets in LOTS of light for hunting, but kind of big for 3d. I love the fiber optic on the cosmic, because as it gets darker out, the pin dims. This way your not losing all your back light. You dont need a bright pin imho, just enough to let you locate the pin. i have found if my pin doesnt light up enough to see it, its too dark to shoot!