The m12 fuel is night and day better than the brushed one. It'll get you by for light duty tasks great. It has a lot more power than that brushed one. But, having all three, the M18 fuel hackzall is not that much bigger or heavier, but cuts so quick and smooth with so much power it will replace using any other Sawzall for 95% of your tasks. Depends what you're mainly cutting with it.