RE: Downside to 1 Pin Sight?
The only real downsides are having to move it for a longer shot in the field with a deer in front of you. Or the most common is forgetting where you had it set and shooting for the wrong yardage. I have sailed a few arrows over my target because I forgot to move my sight after changing from 40 to 20 yards.
Other than that they are great, I like them.
Paul