Wayne, that sure looks familiar.
ten years ago I made something similar by bolting a large narrow backhoe bucket to the underside of my Front End Loader bucket. Called it a "halfback hoe". Making it the way I did means it didn't have the extra bucket curling motion of the one in your picture...but it had all the other features including using the FEL dump cylinders to curl the dipper stick boom. And having to back up to the side to dump it. Clumsy, but it got used it for a variety of jobs for several years.
I originally made it up simply because I needed to dig a shallow long trench, had the bucket in my scrap pile, and didn't have the money to buy a three point backhoe. It was a crude tool - but so is the one by Golden Bell in your picture. The limitation is depth, not strength. They don't dig deep. Now that I have a 3pt hoe I can better evaluate the old "half back" and have concluded that where it really shone was in trenching in hard rocky soil. For that it was worthwhile. That curling motion would take a full bite out of the hardest ground imaginable - ground that is almost impossible to dig by hand became easy. For soft loam, the advantage is less clear. I'd say that if you are physically capable of digging by hand then a long narrow hand-trenching shovel/spoon like electricians use is probably just as efficient. For trenches through hard rocky ground and clay then a half back type hoe is worth the money. Trenches and planting shallow bushes were what it did best.
rScotty