My concern would be that using any metal edge on concrete will eventually damage the top surface of the concrete? The guys who plow snow apparently use some kind of plastic on their snow plow edges.
UHMW Polyethylene cutting edges. Available on Amazon and Ebay.
You could look locally for commercial plastic supplier and see if they have offcuts. Also, they use it for toilet stall partitions, and they folks who do them occasionally have offcuts.
I'd buy the Piranha, and I'll sell you my tooth bar. It's still hanging on my wall. I removed it after trying it for a week.
Just depends on your use and the soils. I'm trying to get cobbles and rocks out of the top foot or so of dirt. To allow tilling for a garden. The Pirahna probably works well grubbing roots and vegetation in non-rocky soils. But not so well for digging in and wiggling rocks until they break free of the dirt they are in. Most of the dedicated loaders in the area have toothed buckets. The more successful local contractors who buy or lease new, all have toothed buckets.
I have a dedicated 48-inch rock bucket, with a 2-inch gap between the slats. It is heavy duty enough to survive in our soils. But, is too close to the lift capacity of the FEL on my tractors. And, I have to rent a skid steer to use it. And, the smaller skid steers have trouble with it in our local soils. So, a dedicated toothed bucket makes sense for my soils.
My place and most of the valley are prehistoric gravel bars which were at the bottom of mountain slopes. Or alluvial fans, from the mountains. So, the soil is rounded river rocks, and jagged talus rocks, in a finer soil matrix. Very hard to dig with a bucket, and a nightmare to dig trenches in. The OSHA trench safety inspector requires trench boxes or 1.25:1 side slopes full depth of the trench. If you need a five foot bury depth to get a water or sewer line below the freeze depth, You are looking at a trench 12-feet wide, because the rocks keep caving in.