2000w, whatever your actual torque number is, is still going to be pedal at least moderately hard at 12%. But a quarter mile is not a long hill, so you should not overheat a motor, or get all that tired pedaling up it.
I do recommend you pedal though, even if it makes it ok without. It will keep your rpm and speed up, making it a more efficient climb.
Chances are though, you will slow to less than 15 mph, and not climb it efficiently. if it was a mile, it would be a problem with a lot of weight, like if you are heavy, or you were towing trailers. So pedaling should keep you closer to 15 mph, if not more. FWIW, if you have a run on that hill, it will cruise up it fairly easy. If you must stop on 12%, pedal hard.
But since they are short, no real problems. you'll just slow down a lot, and should pedal briskly to the top. Your setup should be able to get up a much much longer 8% grade, at 15 mph at least, making it a cool and efficient ride to the top.
With a dd motor, you are not needing torque to get up a steep hill, as you are needing total power. This power, 2000w worth, does mean you have more torque than the same motor with 1000w. But its IMO, the power that will make it possible to get to the top, not torque, which decreases with rpm. Its being able to pull more than 1000w at 15 mph plus that gets you up hills with a dd.
With a mid drive, then you can shift down, and get more torque from little power.
If you are running a typical dd hubmotor, you are already about at the motors power limitations, more will just melt it faster. But,,,, the hill is short, so 3000w will get you up it faster. 8)
