I noticed that some HH bows have limb tip overlays and some do not. Is there advantages or disadvantages with/without tip overlays?
Not really. You'll also notice that he puts a fiberglass wedge in the limb tip as well (or is it wood?). Regardless, it's there to strengthen the tip. Limb tip overlays help take some of the wear from fast flite strings though so I ordered my recent Hill with tip overlays. No overlays is the traditional Hill style. Theoretically, less weight on the limb tips means faster limbs, greater efficiency, etc., but the tip overlays on a Hill bow are quite small, and I think it would take a pretty good chrono to detect a difference, and shooters won't notice any difference.