Biggest advantage I can see, if you cant the bow, rather than hold it completely horizontal,your shot will still be on. With a traditional crossbow scope with a multi-reticle, if you cant the bow on a longer shot your arrow will go where your crosshairs are canted to. (they swing right or left when you bring the bow out of level)
The HHA Optimizer brings the POI to the center of the scope. If you can hold your crossbow perfectly level every shot, you don't need one. If you need to be able to hold out of level for any reason (like to clear a treelimb) then this solves the problems associated with canting your bow to the right or left.
We have them in stock if anyone needs one.