Originally Posted by Calsun

From the Specialized website "All full power motors provide 250w of nominal output. "Nominal" means the power output that the motor can maintain over a defined period of time in a standardized test. Depending on the specific motor type, a full power turbo bike will provide the rider with 400 to 560 watts of peak power. Torque, which is measured in newton meters (Nm), refers to the acceleration power and climbing performance the motor provides. A motor that provides more torque will make it easier for you to accelerate and climb steep inclines. Full power motors provide 50 to 90 Nm of torque at the lower cadences of 50 to 60 rpm for steady, natural acceleration and smooth climbing. As you pedal faster, the motor gradually provides less torque rather than dropping off sharply. The goal is to mimic the feel of riding without motor assist."

For hills the Nm rating for a drivetrain provides a better indication of how much pedal assistance can be provided. The heavier the bike and its wheels the more Nm one needs from the bike motor on inclines. My road e-bike that weighs only 27 lbs has a drivetrain that provides 320Wh and that is more than enough on any terrain and with any amount of headwind.

Hub drives are cheaper and so they keep the price of the bike down. It is what is used on all the low end bikes for that reason alone. Most people buy based on price and not because of individual components on the bike. I wanted a mid-drive to have a more natural pedal assist experience when riding and as a bonus it is far easier to deal with a flat tire while out riding.