Grndzer - <font color=red>The sight that you are interested in would be legal, HOWEVER, if someone saw or thought you had moved it on the range they could file a protest and you could be DQ'd</font id=red>
The following is from the IBO rule book, (this might help you out)

I.B.O. CLASSES DEFINED

Hunter Class (HC)

A compound, recurve, or longbow with or without sights, may be shot with release aid, finger tab, glove or bare fingers. If a sight is used it will have no more than four (4) fixed or crosshair style pins. Circle pins allowed if all circles are the same size. Arrows must have screw in style points and a minimum of 4 inch vanes or feathers. Only one (1) single stabilizer being less than twelve (12) inches in length from the nearest point of attachment is allowed. A maximum of eighty (80) pounds of peak weight is allowed and will be shot from the yellow stake with a maximum of 35 yards. * - **

If a shooter wins twice while competing in the Hunter Class at a national or world level tournament during one IBO shoot calendar year, that shooter must advance to a higher competitive level the following IBO shoot calendar year. Once this shooter advances to the higher competitive level, he/she must remain at that level for an entire IBO shoot calendar year.