For a modern machine, it's ok. The current "Heavy-Duty" Singer machines are really more "moderate-duty" and suffer from significant reliability and repairability issues. Yes, it can do zigzags and other stitches out of the box without an attachment but, can it stitch through two layers of 1000D ballistic nylon with a polypropylene sheet as a stiffener without complaining AND double as an emergency boat anchor? My all-metal, 10kg model 99k (portable model) can and it was cheaper and can be converted to use a treadle or manual crank :P.
Modern industrial sewing machines are generally still powered by a belt that passes through the table, though now the belt leads instead to a large servo motor slung to the table's underside. But that does leave the machine heads more-or-less compatible with the old treadle tables