I have installed them and tried them and to me they have three major drawbacks.
1)They distract you from focusing on the target. The sight should be as simple and non-busy as possible otherwise your focusing your attention on the sight and not concentrating on the target. I saw these sights turn some good shooters into trigger punching fools because they couldnt get the rings to stay completely still. They were not moving any more than they ever had but the sight made them think they were.
2)It required a lot of set up time and each different bow had its own set of problems especially those with short sight windows. sometimes it required people to change their anchor point which I did not like. The sight should adapt to you not vice-versa.
3)Say goodbye to simple quick sight adjustments. Elevation is not bad on some mounts but windage adjustments can be a real headache. Also is more prone to damage in the field.
All in all it just over complicates such a simple job. Tell him to save his money.