Competition use as in PRS-style matches? Honestly, you don't see them very often on match guns. I have read up on the concept behind using one to quickly acquire your target then dropping behind your optic for the shot (same idea as how some employ them on a spotting scope, usually co-witnessed with the reticle around 600 or so yards) and have thought about trying it with a cheap rds to see if it works for me but I've instead just worked on being able to pick up the target faster by sighting down the elevation turret. I'm assuming this is what you're wanting the rds setup for and not as an actual aiming device like guys use in say 3-gun?