I have the Makita brand brushless tools. My brushless impact, drill/driver, and hammer drill, last considerably longer than my brushed jigsaw, that all use lithium batteries. I don't have brushed lithium drills or drivers, as I jumped into the lithium battery powered tools, waiting for the brushless three speed to come out.
The three speed that controls the torque and speed is the best, cordless tool I have ever used. I later bought a combo kit that didn't have the three speed option impact driver, just the brushless impact driver, also came with a hammerdrill. Both sets brushless. I really like the speed option, I suggest everyone try the three different speeds/torques on different materials. You won't go back. I have used my three speed on metals screws in plastic with great results, on low setting.
I know it is a different brand but the key is the different torque settings really. The impact will impact all day, just keep hammering away. there is some finesse with it I guess, just like any other tool. It adds another level of control. so it is controlled electrically somehow. I would guess changing the resistance, lowering the current.
Try one before choosing you won't be disappointed. I assume the Milwaukee is just like the Makita, they usually are very similar, both great tools. Milwaukee offers more tools, many more tools, despite Makita coming to market sooner. I would cross shop them. If I had to buy again, I would probably go with Milwulee because of the variety tools. 50 or 60 tools, some of them really cool. I wish I had those options with Makita. I don't regret my purchase though, compared to my De Walt set with 6 batteries, it saved me a great deal of time.
I can pull lug nuts off that are torque to 90lbs/ft with it the impact driver.
The M12 stuff isn't what I would consider large and may even be smaller than average.