I've played on chipped reeds that were adequate, but never were they optimal. In the heat of battle (so to speak), you may have to use a damaged reed until you have the opportunity to replace it. But, by the end of a scene (in musical theater) or the end of a set (in performance work), I've always moved to another one that's intact.
In a similar vein, I've yet to encounter an intact reed (in Van Dornes, at least) out of the box that was not useable. Some are better than others, but all of them will do for me.
A chipped or broken corner will result in an unbalanced reed that is unresponsive and prone to squeaks. If there is a small bit of material broken off in the center area of the tip of the reed, the effect is often minimal. You know the saying: "Location, location, location".