You can shoot any sight as long as you dont move it. I have used a sure-loc challenger and supreme in hunter class at all the nationals and world championship with no problems. Here is the rule that allows it C-3.
C. Sights, Overdraws, Unusual Equipment, Etc.
1. Overdraws are permitted in all classes except TRD, YTRD, FTRD, LB, RU.
2. There is no limit to the number of pins on a sight.
3. A sight used in a fixed-pin class may not be adjusted once the archer enters the shooting course.
4. Sights that project a laser light or other aiming dot on the target are illegal in all classes.
5. An archer using new or unusual equipment not addressed by class definitions or elsewhere in these rules will be required to shoot in one of the open classes until the IBO Board of Directors makes a ruling on the proper class for the equipment.
6. A verifier or clarifier style peep sight will be allowed in all classes that permit the use of sights.
IV.