My understanding has always been that the weight of the chain is as if not more important than the working load. Weight is important because it increases catenary which keeps more chain on the bottom. More chain on the bottom is good because it takes energy to lift t so more on the bottom means more energy to lift the chain - i.e., better energy absorption by your chain. In addition if the load on the chain is parallel to the bottom it will tend to dig your anchor in. The steeper the angle between the chain and the bottom the more "up" load you have on the anchor and the more like it is to break the anchor out.
As far as chain working load goes, my mooring, which is rated for a 50' boat in winds up to 60 knots has only 1/2" ACCO long link mooring chain (WLL = 6,900 lbs) for the top chain. The bottom chain is 1-1/4" and is there for two reasons. First its weight (~15 lbs per foot) keeps it on the bottom in all but bad storms and second it is strong enough to lift my mooring stone (10,000 lbs) out of the mud and off the bottom. Actually in normal weather I am moored to my bottom chain (600 lbs) since normal loads aren't enough to pull it out of the mud and put any load on the granite mooring stone. My 36;, 20,000 lb boat has ridden out several 60 knot storms on that mooring. I do use two pennants (1" Yale polydyne) for storms.
Edited to add - While G4 chain is stronger than BBB, the G4 chain is also more brittle and thus more prone to fracturing rather than deforming if overloaded.