>>2948593 (OP)
I did a 12’x20’x4” slab for a greenhouse with the “mud mixer” and while the concrete turned out perfectly fine, the pour took ages compared to a tumble and dump. IMO it would be ideal for making mud or mortar for block work, but for my application, it meant that most of the crew I assembled basically was shovel leaning when they weren’t doing the grilling. There’s a bigger one, that would probably be better, but my local hardware store only had the one in OP’s picture.