I really can't see either of those devices being better than a peep sight.

a 1/4" or even a 3/16" peep set up behind a nice sight with good pins will allow you to shoot in just about any REASONABLE lighting condition. Any later than that, and your asking for trouble. Some guys will even shoot a 5/16" peep, which is absolutely huge to look through. I've been around bows for a long time, and have met plenty of pro shooters, been to a bunch of outdoor, 3d and and indoor spot shoots, and have never seen anybody use one of those.Why is that?