I think your friends are either misinformed or just making stuff up. Why would they effect the arrow on shots past 30 yards? It's not like the arrow would say "well, here's 30 yards I think I will turn to the right this time". Once the arrow leaves the bow nothing on that bow has any effect on the arrow. Educate your friends.

They are a great no nonsence rest that has no moving parts to fail or break.